<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e64ef-1077-7214-8163-4810b4141dc8,g:15bcf348-bf22-41bc-8e3b-d5547e8cdc4f-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://pinnaclewest.com/role/CoverPage" xlink:type="simple" xlink:href="pnw-20260630.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_019e64ef-1730-7428-b2ea-1e9368ce7077" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntitiesTable_019e64ef-1730-7428-b2ea-1e9368ce7077" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-1730-74f2-9e3e-74572c0a690f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_019e64ef-1730-7428-b2ea-1e9368ce7077" xlink:to="loc_dei_LegalEntityAxis_019e64ef-1730-74f2-9e3e-74572c0a690f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-74f2-9e3e-74572c0a690f_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-74f2-9e3e-74572c0a690f" xlink:to="loc_dei_EntityDomain_019e64ef-1730-74f2-9e3e-74572c0a690f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-7d12-a3d7-131c82e313bc" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-74f2-9e3e-74572c0a690f" xlink:to="loc_dei_EntityDomain_019e64ef-1730-7d12-a3d7-131c82e313bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7024-8eac-f8c4fa806df2" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-1730-7d12-a3d7-131c82e313bc" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7024-8eac-f8c4fa806df2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019e64ef-1730-754d-bd20-d2b4a9910a0e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_DocumentType_019e64ef-1730-754d-bd20-d2b4a9910a0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_019e64ef-1730-71b9-a345-ef298f57a5ba" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_DocumentQuarterlyReport_019e64ef-1730-71b9-a345-ef298f57a5ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019e64ef-1730-75da-995d-f3e2b9d65901" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_DocumentPeriodEndDate_019e64ef-1730-75da-995d-f3e2b9d65901" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019e64ef-1730-7ff2-96c8-89ce0cc8954b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_DocumentTransitionReport_019e64ef-1730-7ff2-96c8-89ce0cc8954b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019e64ef-1730-7b5e-b3a7-93efb824dd8d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityFileNumber_019e64ef-1730-7b5e-b3a7-93efb824dd8d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019e64ef-1730-779b-b539-997a9e13d958" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityRegistrantName_019e64ef-1730-779b-b539-997a9e13d958" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019e64ef-1730-7574-aaf9-81cb4c4a9a52" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityTaxIdentificationNumber_019e64ef-1730-7574-aaf9-81cb4c4a9a52" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019e64ef-1730-75a8-8e3c-574caf0970bc" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019e64ef-1730-75a8-8e3c-574caf0970bc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019e64ef-1730-7de8-aaa5-816f9a554a99" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityAddressAddressLine1_019e64ef-1730-7de8-aaa5-816f9a554a99" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019e64ef-1730-7a76-8a99-774552a10f58" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityAddressCityOrTown_019e64ef-1730-7a76-8a99-774552a10f58" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019e64ef-1730-707b-996e-1aa8cd64230f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityAddressStateOrProvince_019e64ef-1730-707b-996e-1aa8cd64230f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019e64ef-1730-7b9f-af80-d3529f1f03b0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityAddressPostalZipCode_019e64ef-1730-7b9f-af80-d3529f1f03b0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019e64ef-1730-7df1-81ac-e5901e772577" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_CityAreaCode_019e64ef-1730-7df1-81ac-e5901e772577" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019e64ef-1730-7eaa-824d-e726a01fbfa9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_LocalPhoneNumber_019e64ef-1730-7eaa-824d-e726a01fbfa9" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019e64ef-1730-7071-ab29-3e62657ece08" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_Security12bTitle_019e64ef-1730-7071-ab29-3e62657ece08" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019e64ef-1730-7735-9e99-6f00370161fd" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_TradingSymbol_019e64ef-1730-7735-9e99-6f00370161fd" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019e64ef-1730-7982-a4b0-d704403a2767" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_SecurityExchangeName_019e64ef-1730-7982-a4b0-d704403a2767" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019e64ef-1730-7933-af84-fce75346daf8" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityCurrentReportingStatus_019e64ef-1730-7933-af84-fce75346daf8" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019e64ef-1730-786e-80d1-5305e1778bb7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityInteractiveDataCurrent_019e64ef-1730-786e-80d1-5305e1778bb7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019e64ef-1730-7c9d-85f9-d50eca8b063c" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityFilerCategory_019e64ef-1730-7c9d-85f9-d50eca8b063c" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_019e64ef-1730-7b35-a487-d26a5c83f4f2" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntitySmallBusiness_019e64ef-1730-7b35-a487-d26a5c83f4f2" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019e64ef-1730-77ed-83cc-8468277c3ae6" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityEmergingGrowthCompany_019e64ef-1730-77ed-83cc-8468277c3ae6" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019e64ef-1730-7acb-8080-ba520f64bf15" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityShellCompany_019e64ef-1730-7acb-8080-ba520f64bf15" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019e64ef-1730-7e0d-88f6-f1da09e54b16" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019e64ef-1730-7e0d-88f6-f1da09e54b16" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019e64ef-1730-7e42-a9f6-14e37ed99dff" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_EntityCentralIndexKey_019e64ef-1730-7e42-a9f6-14e37ed99dff" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019e64ef-1730-7682-8a7b-5e2c331776d7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_AmendmentFlag_019e64ef-1730-7682-8a7b-5e2c331776d7" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019e64ef-1730-7b52-a11b-03db372871fa" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_CurrentFiscalYearEndDate_019e64ef-1730-7b52-a11b-03db372871fa" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019e64ef-1730-7d03-8d99-781293cc24f5" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_DocumentFiscalYearFocus_019e64ef-1730-7d03-8d99-781293cc24f5" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019e64ef-1730-78aa-9af6-7080c2adce52" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e64ef-1730-7744-a5bd-e015d2da22b1" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019e64ef-1730-78aa-9af6-7080c2adce52" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY" xlink:type="simple" xlink:href="pnw-20260630.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-1730-7787-b7cf-d2f3b71d2080" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-1730-7121-9bc1-a718d3ed53a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-7787-b7cf-d2f3b71d2080" xlink:to="loc_us-gaap_StatementTable_019e64ef-1730-7121-9bc1-a718d3ed53a3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-1730-7c7b-9048-3ed496fb47ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-1730-7121-9bc1-a718d3ed53a3" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-1730-7c7b-9048-3ed496fb47ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e64ef-1730-7c7b-9048-3ed496fb47ff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-1730-7c7b-9048-3ed496fb47ff" xlink:to="loc_us-gaap_EquityComponentDomain_019e64ef-1730-7c7b-9048-3ed496fb47ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-1730-7c7b-9048-3ed496fb47ff" xlink:to="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e64ef-1730-7b3e-8666-ea7eb07d4099" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:to="loc_us-gaap_CommonStockMember_019e64ef-1730-7b3e-8666-ea7eb07d4099" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019e64ef-1730-7150-86bd-c788798b5aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019e64ef-1730-7150-86bd-c788798b5aeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e64ef-1730-75e7-bb75-a516ace81f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:to="loc_us-gaap_RetainedEarningsMember_019e64ef-1730-75e7-bb75-a516ace81f6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-1730-7385-bce0-9727ac3e26df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-1730-7385-bce0-9727ac3e26df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019e64ef-1730-7b2f-85c7-735f4393741b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-1730-73ee-99b3-ea70d21874b1" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019e64ef-1730-7b2f-85c7-735f4393741b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-7787-b7cf-d2f3b71d2080" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019e64ef-1730-73c9-9092-03ea4b0a5db3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_CommonStockSharesIssued_019e64ef-1730-73c9-9092-03ea4b0a5db3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-708c-a084-f4920a6d3d7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-708c-a084-f4920a6d3d7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_019e64ef-1730-7f4b-97ae-290524cf5800" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_TreasuryStockCommonShares_019e64ef-1730-7f4b-97ae-290524cf5800" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e64ef-1730-7d6f-a3f2-6d716a664eac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_ProfitLoss_019e64ef-1730-7d6f-a3f2-6d716a664eac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e64ef-1730-7b0c-9a27-b23c045bce34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e64ef-1730-7b0c-9a27-b23c045bce34" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_019ecb71-6ac6-7f02-8bb8-e37e292c0bec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_DividendsCommonStockCash_019ecb71-6ac6-7f02-8bb8-e37e292c0bec" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019e64ef-1730-7a7b-9928-984caa9ec5da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019e64ef-1730-7a7b-9928-984caa9ec5da" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_StockIssuedDuringPeriodValueNewIssuesNet_019e64ef-1730-78e5-be60-33b358c37a6a" xlink:href="pnw-20260630.xsd#pnw_StockIssuedDuringPeriodValueNewIssuesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_pnw_StockIssuedDuringPeriodValueNewIssuesNet_019e64ef-1730-78e5-be60-33b358c37a6a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_019ecb71-6ac6-77b6-9de0-42ecb06602bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_019ecb71-6ac6-77b6-9de0-42ecb06602bf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_019e64ef-1730-7723-923f-c44c7fdf88e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-1730-796b-ae41-1d352dd108a8" xlink:to="loc_us-gaap_StockholdersEquityOther_019e64ef-1730-7723-923f-c44c7fdf88e0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019e64ef-1730-75ed-9cb7-11cd83692928" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-7002-9593-905c34ffc3bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_019e64ef-1730-7e89-b613-df3eee7b0dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFINCOME" xlink:type="simple" xlink:href="pnw-20260630.xsd#ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFINCOME"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFINCOME" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-1730-7fd2-8be4-2c8441c137d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_StatementTable_019e64ef-1730-7fd2-8be4-2c8441c137d9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-1730-75b9-8019-03e1ceca0bc4" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-1730-7fd2-8be4-2c8441c137d9" xlink:to="loc_dei_LegalEntityAxis_019e64ef-1730-75b9-8019-03e1ceca0bc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-75b9-8019-03e1ceca0bc4_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-75b9-8019-03e1ceca0bc4" xlink:to="loc_dei_EntityDomain_019e64ef-1730-75b9-8019-03e1ceca0bc4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-7bda-a22b-6aa3cfec1611" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-75b9-8019-03e1ceca0bc4" xlink:to="loc_dei_EntityDomain_019e64ef-1730-7bda-a22b-6aa3cfec1611" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7ebf-9832-7fbc5bc14d5b" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-1730-7bda-a22b-6aa3cfec1611" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7ebf-9832-7fbc5bc14d5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e64ef-1730-7b2c-a181-8ed61df75af9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_Revenues_019e64ef-1730-7b2c-a181-8ed61df75af9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e64ef-1730-7bea-94a1-14f9e1f489d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:to="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e64ef-1730-7bea-94a1-14f9e1f489d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations_019e64ef-1730-7d8a-b360-db7bbf71ab27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations_019e64ef-1730-7d8a-b360-db7bbf71ab27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSoldDepreciationAndAmortization_019e64ef-1730-79e7-b38e-ee23be85e484" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSoldDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSoldDepreciationAndAmortization_019e64ef-1730-79e7-b38e-ee23be85e484" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesExcludingIncomeAndExciseTaxes_019e64ef-1730-7556-971a-5b0409c274b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxesExcludingIncomeAndExciseTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:to="loc_us-gaap_TaxesExcludingIncomeAndExciseTaxes_019e64ef-1730-7556-971a-5b0409c274b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCostAndExpenseOperating_019e64ef-1730-7fb5-b2ae-0b837ac8ae56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCostAndExpenseOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:to="loc_us-gaap_OtherCostAndExpenseOperating_019e64ef-1730-7fb5-b2ae-0b837ac8ae56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019e64ef-1730-7717-9d4c-8b5ab8ce7830" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e64ef-1730-74e6-b965-8ea54fa7b6ea" xlink:to="loc_us-gaap_CostsAndExpenses_019e64ef-1730-7717-9d4c-8b5ab8ce7830" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e64ef-1730-7987-b238-7afe1084ad14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_OperatingIncomeLoss_019e64ef-1730-7987-b238-7afe1084ad14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019e64ef-1730-752f-b361-7c9f6ba48b3e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019e64ef-1730-752f-b361-7c9f6ba48b3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019e64ef-1730-7b34-b78d-6e8bd623de3e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionAndOtherPostretirementBenefitExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:to="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019e64ef-1730-7b34-b78d-6e8bd623de3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncome_019e64ef-1730-7382-8841-91c60a06eade" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:to="loc_us-gaap_OtherNonoperatingIncome_019e64ef-1730-7382-8841-91c60a06eade" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_019e64ef-1730-7b51-9854-b34dd7de9867" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:to="loc_us-gaap_OtherNonoperatingExpense_019e64ef-1730-7b51-9854-b34dd7de9867" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019e64ef-1730-7576-ad98-119f487b54fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e64ef-1730-70b3-b6eb-3efa2543905b" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019e64ef-1730-7576-ad98-119f487b54fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseAbstract_019e64ef-1730-7ed2-a673-5f52042de144" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_InterestExpenseAbstract_019e64ef-1730-7ed2-a673-5f52042de144" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestCostsIncurred_019e64ef-1730-74bd-87fe-bd5e0fbdb1b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestCostsIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_019e64ef-1730-7ed2-a673-5f52042de144" xlink:to="loc_us-gaap_InterestCostsIncurred_019e64ef-1730-74bd-87fe-bd5e0fbdb1b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions_019e64ef-1730-7d92-9f92-bd6e98f87b84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_019e64ef-1730-7ed2-a673-5f52042de144" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions_019e64ef-1730-7d92-9f92-bd6e98f87b84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e64ef-1730-795c-88cf-ae967ee277f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_019e64ef-1730-7ed2-a673-5f52042de144" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e64ef-1730-795c-88cf-ae967ee277f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-7a10-b271-a9e047f8593b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_IncomeLossIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-7a10-b271-a9e047f8593b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e64ef-1730-715b-a51e-e887470e42ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e64ef-1730-715b-a51e-e887470e42ea" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e64ef-1730-7b41-9820-c4a27756e376" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_ProfitLoss_019e64ef-1730-7b41-9820-c4a27756e376" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-1730-74ff-aae2-4084dfded2ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-1730-74ff-aae2-4084dfded2ff" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e64ef-1730-78f2-b1b4-ced3f9e89cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-74f7-a1f1-b4ab12927936" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e64ef-1730-78f2-b1b4-ced3f9e89cb5" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" xlink:type="simple" xlink:href="pnw-20260630.xsd#ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-1730-7095-83e3-aea76c420799" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:to="loc_us-gaap_StatementTable_019e64ef-1730-7095-83e3-aea76c420799" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-1730-7ab1-a6b0-303d3ee19bf7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-1730-7095-83e3-aea76c420799" xlink:to="loc_dei_LegalEntityAxis_019e64ef-1730-7ab1-a6b0-303d3ee19bf7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-7ab1-a6b0-303d3ee19bf7_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-7ab1-a6b0-303d3ee19bf7" xlink:to="loc_dei_EntityDomain_019e64ef-1730-7ab1-a6b0-303d3ee19bf7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-783a-861c-47ae93b01c59" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-7ab1-a6b0-303d3ee19bf7" xlink:to="loc_dei_EntityDomain_019e64ef-1730-783a-861c-47ae93b01c59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-719a-99ec-7f2f7a127355" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-1730-783a-861c-47ae93b01c59" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-719a-99ec-7f2f7a127355" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e64ef-1730-7c19-abfe-91c00a3e4bcc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:to="loc_us-gaap_ProfitLoss_019e64ef-1730-7c19-abfe-91c00a3e4bcc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_019e64ef-1730-773b-a4ff-91fa9922b5ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_019e64ef-1730-773b-a4ff-91fa9922b5ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019e64ef-1730-7a9b-a900-74c822dece9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_019e64ef-1730-773b-a4ff-91fa9922b5ac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019e64ef-1730-7a9b-a900-74c822dece9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e64ef-1730-71dc-9873-9db0efcd98e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_019e64ef-1730-773b-a4ff-91fa9922b5ac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e64ef-1730-71dc-9873-9db0efcd98e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-7e93-b6f5-ebff992b588c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019e64ef-1730-7e93-b6f5-ebff992b588c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-1730-74a8-b57b-01106ecdce38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-1730-74a8-b57b-01106ecdce38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_019e64ef-1730-72c1-9aa3-4f3e692b3e45" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-79d6-a884-dcbab4f57e2c" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_019e64ef-1730-72c1-9aa3-4f3e692b3e45" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEParenthetical" xlink:type="simple" xlink:href="pnw-20260630.xsd#ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEParenthetical"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-1730-7b0c-871f-dc31a52101cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-1730-70f1-9c65-2d8c9405f785" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-7b0c-871f-dc31a52101cf" xlink:to="loc_us-gaap_StatementTable_019e64ef-1730-70f1-9c65-2d8c9405f785" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-1730-7b8a-b3d1-897a6e711371" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-1730-70f1-9c65-2d8c9405f785" xlink:to="loc_dei_LegalEntityAxis_019e64ef-1730-7b8a-b3d1-897a6e711371" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-7b8a-b3d1-897a6e711371_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-7b8a-b3d1-897a6e711371" xlink:to="loc_dei_EntityDomain_019e64ef-1730-7b8a-b3d1-897a6e711371_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-7954-b61c-aac7db4b0c84" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-7b8a-b3d1-897a6e711371" xlink:to="loc_dei_EntityDomain_019e64ef-1730-7954-b61c-aac7db4b0c84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7b0a-a829-edbcb51fabdf" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-1730-7954-b61c-aac7db4b0c84" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7b0a-a829-edbcb51fabdf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax_019e64ef-1730-7447-8341-74481c1fcf52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-7b0c-871f-dc31a52101cf" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax_019e64ef-1730-7447-8341-74481c1fcf52" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="pnw-20260630.xsd#ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-1730-714e-a960-70fa98f4c538" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-1730-7ea2-aaf9-969ff1cf2002" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-714e-a960-70fa98f4c538" xlink:to="loc_us-gaap_StatementTable_019e64ef-1730-7ea2-aaf9-969ff1cf2002" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-1730-750f-bfb6-c66bcef317c7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-1730-7ea2-aaf9-969ff1cf2002" xlink:to="loc_dei_LegalEntityAxis_019e64ef-1730-750f-bfb6-c66bcef317c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-750f-bfb6-c66bcef317c7_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-750f-bfb6-c66bcef317c7" xlink:to="loc_dei_EntityDomain_019e64ef-1730-750f-bfb6-c66bcef317c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-1730-7d14-b075-0319a37fc221" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-1730-750f-bfb6-c66bcef317c7" xlink:to="loc_dei_EntityDomain_019e64ef-1730-7d14-b075-0319a37fc221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7238-b60a-6550cfde33bf" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-1730-7d14-b075-0319a37fc221" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-1730-7238-b60a-6550cfde33bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-714e-a960-70fa98f4c538" xlink:to="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e64ef-1730-7b10-82f8-1761c42fdad4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e64ef-1730-7b10-82f8-1761c42fdad4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_019e64ef-1730-76c0-ad74-464b52a7be76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableGrossCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_AccountsReceivableGrossCurrent_019e64ef-1730-76c0-ad74-464b52a7be76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_019e64ef-1730-7c26-aea2-4fcff7f2c80f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_019e64ef-1730-7c26-aea2-4fcff7f2c80f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019e64ef-1730-7769-a3a9-a3cfeaa360f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019e64ef-1730-7769-a3a9-a3cfeaa360f3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherInventorySupplies_019e64ef-1730-7674-aebd-fe1e6acc527b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherInventorySupplies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_OtherInventorySupplies_019e64ef-1730-7674-aebd-fe1e6acc527b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedInventoryOtherFossilFuel_019e64ef-1730-7e41-9e24-8173323516e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnergyRelatedInventoryOtherFossilFuel"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_EnergyRelatedInventoryOtherFossilFuel_019e64ef-1730-7e41-9e24-8173323516e6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedges_019e64ef-1730-7786-b99d-0e9b4be24a7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedges_019e64ef-1730-7786-b99d-0e9b4be24a7a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetCurrent_019e64ef-1730-7e13-821e-e9d58174a823" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetCurrent_019e64ef-1730-7e13-821e-e9d58174a823" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OtherRegulatoryAssetsCurrent_019e64ef-1730-7228-8328-e2c767e2e54a" xlink:href="pnw-20260630.xsd#pnw_OtherRegulatoryAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_pnw_OtherRegulatoryAssetsCurrent_019e64ef-1730-7228-8328-e2c767e2e54a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_019e64ef-1730-762d-897f-a9240e207a9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_OtherAssetsCurrent_019e64ef-1730-762d-897f-a9240e207a9e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019e64ef-1730-70a9-9168-c6ecd8580cce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e64ef-1730-77ed-865d-8d181605f520" xlink:to="loc_us-gaap_AssetsCurrent_019e64ef-1730-70a9-9168-c6ecd8580cce" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:href="pnw-20260630.xsd#pnw_InvestmentsAndOtherAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:to="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_019e64ef-1730-791a-942d-17920202f9bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_019e64ef-1730-791a-942d-17920202f9bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CoalReclamationandUnionTrust_019e64ef-1730-72aa-932e-f6cbe4cca10a" xlink:href="pnw-20260630.xsd#pnw_CoalReclamationandUnionTrust"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:to="loc_pnw_CoalReclamationandUnionTrust_019e64ef-1730-72aa-932e-f6cbe4cca10a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditRiskDerivativeAssetsAtFairValue_019e64ef-1730-7ced-8e69-962fd33ea1a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditRiskDerivativeAssetsAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:to="loc_us-gaap_CreditRiskDerivativeAssetsAtFairValue_019e64ef-1730-7ced-8e69-962fd33ea1a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019e64ef-1730-7627-8970-fb28f007d3b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019e64ef-1730-7627-8970-fb28f007d3b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TotalInvestmentsAndOtherAssets_019e64ef-1730-7110-83b1-bd46c197da3e" xlink:href="pnw-20260630.xsd#pnw_TotalInvestmentsAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsAndOtherAssetsAbstract_019e64ef-1730-70ab-a944-787d16638da6" xlink:to="loc_pnw_TotalInvestmentsAndOtherAssets_019e64ef-1730-7110-83b1-bd46c197da3e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019e64ef-1730-7302-88e8-a0ddf3e0a3b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019e64ef-1730-7302-88e8-a0ddf3e0a3b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e64ef-1730-789e-8ce0-31653a4937ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e64ef-1730-789e-8ce0-31653a4937ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e64ef-1730-7029-884c-3814f8f80b3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e64ef-1730-7029-884c-3814f8f80b3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ConstructionWorkInProgressGross_019e64ef-1730-7807-a2d5-f33d6bfbf895" xlink:href="pnw-20260630.xsd#pnw_ConstructionWorkInProgressGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_pnw_ConstructionWorkInProgressGross_019e64ef-1730-7807-a2d5-f33d6bfbf895" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesPropertyPlantAndEquipmentSaleLeasebackNet_019e64ef-1730-703b-9bfa-c627768f01b1" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesPropertyPlantAndEquipmentSaleLeasebackNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_pnw_PublicUtilitiesPropertyPlantAndEquipmentSaleLeasebackNet_019e64ef-1730-703b-9bfa-c627768f01b1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e64ef-1730-7d63-8075-84a119ca350a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e64ef-1730-7d63-8075-84a119ca350a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelNetOfAmortization_019e64ef-1730-73d9-9c76-9f5ddad3edf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NuclearFuelNetOfAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_us-gaap_NuclearFuelNetOfAmortization_019e64ef-1730-73d9-9c76-9f5ddad3edf2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019e64ef-1730-73bb-aeed-73ec27bf2150" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e64ef-1730-7ca5-80e1-c816a8bcb7e4" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019e64ef-1730-73bb-aeed-73ec27bf2150" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCostsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:to="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsNoncurrent_019e64ef-1730-7e13-a30e-21c338f2312b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:to="loc_us-gaap_RegulatoryAssetsNoncurrent_019e64ef-1730-7e13-a30e-21c338f2312b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e64ef-1730-760c-8417-94e71e979bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e64ef-1730-760c-8417-94e71e979bb8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_019e64ef-1730-7f64-aa99-82f074d7e659" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_019e64ef-1730-7f64-aa99-82f074d7e659" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDeferredCostsNet_019e64ef-1730-7ac1-9b1d-a39069f6cbff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDeferredCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:to="loc_us-gaap_OtherDeferredCostsNet_019e64ef-1730-7ac1-9b1d-a39069f6cbff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TotalDeferredDebits_019e64ef-1730-71ed-8e38-65a76139c6c1" xlink:href="pnw-20260630.xsd#pnw_TotalDeferredDebits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCostsAbstract_019e64ef-1730-7358-ad13-86479b93a441" xlink:to="loc_pnw_TotalDeferredDebits_019e64ef-1730-71ed-8e38-65a76139c6c1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e64ef-1730-7bf9-a589-1722595a19b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e64ef-1730-7212-b96d-6f05d2738efa" xlink:to="loc_us-gaap_Assets_019e64ef-1730-7bf9-a589-1722595a19b4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-1730-714e-a960-70fa98f4c538" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019e64ef-1730-76cc-ae35-c4509bc25ca2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_AccountsPayableCurrent_019e64ef-1730-76cc-ae35-c4509bc25ca2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_019e64ef-1730-7139-8fc3-0a97ceabffb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxesPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_TaxesPayableCurrent_019e64ef-1730-7139-8fc3-0a97ceabffb4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrent_019e64ef-1730-747c-9bee-78c30f9d94e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_InterestPayableCurrent_019e64ef-1730-747c-9bee-78c30f9d94e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrent_019e64ef-1730-7845-9110-1bba8f899f34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_DividendsPayableCurrent_019e64ef-1730-7845-9110-1bba8f899f34" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_019e64ef-1730-7f8f-9cf9-f79e9fd1bbc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_ShortTermBorrowings_019e64ef-1730-7f8f-9cf9-f79e9fd1bbc1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019e64ef-1730-7c50-b17a-dee4ef0914e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_LongTermDebtCurrent_019e64ef-1730-7c50-b17a-dee4ef0914e9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019e64ef-1730-708e-bbd5-bc29d42c973e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019e64ef-1730-708e-bbd5-bc29d42c973e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgesLiabilities_019e64ef-1730-70d1-af69-830cf892a0a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgesLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgesLiabilities_019e64ef-1730-70d1-af69-830cf892a0a2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryLiabilityCurrent_019f470a-b29a-79e4-9cb6-7ed6a3c9147a" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerRegulatoryLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryLiabilityCurrent_019f470a-b29a-79e4-9cb6-7ed6a3c9147a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationCurrent_019e64ef-1730-715c-af76-3d535a6c42d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_AssetRetirementObligationCurrent_019e64ef-1730-715c-af76-3d535a6c42d6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_019e64ef-1730-78d5-8075-cfece933b77a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_019e64ef-1730-78d5-8075-cfece933b77a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityCurrent_019e64ef-1730-7d70-a35d-cacdea934916" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_RegulatoryLiabilityCurrent_019e64ef-1730-7d70-a35d-cacdea934916" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_019e64ef-1730-792f-bc41-08d1741b0cc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_019e64ef-1730-792f-bc41-08d1741b0cc1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019e64ef-1730-7b7e-b961-aa2dcede7719" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e64ef-1730-7282-944d-0c364400fdee" xlink:to="loc_us-gaap_LiabilitiesCurrent_019e64ef-1730-7b7e-b961-aa2dcede7719" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:to="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019e64ef-1730-73af-9bd9-07979794600e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019e64ef-1730-73af-9bd9-07979794600e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019e64ef-1730-76b4-a574-123100fc3ec0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019e64ef-1730-76b4-a574-123100fc3ec0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityNoncurrent_019e64ef-1730-79c4-9a98-b71ac1a2506e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_RegulatoryLiabilityNoncurrent_019e64ef-1730-79c4-9a98-b71ac1a2506e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_019e64ef-17ea-7249-8f88-f551f06b0f00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_019e64ef-17ea-7249-8f88-f551f06b0f00" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationsNoncurrent_019e64ef-17ea-724e-a7d2-098b81694e99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_AssetRetirementObligationsNoncurrent_019e64ef-17ea-724e-a7d2-098b81694e99" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019e64ef-17ea-7b4b-835a-5decd4e2014c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019e64ef-17ea-7b4b-835a-5decd4e2014c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RecordedUnconditionalPurchaseObligation_019e64ef-17ea-7e76-b172-41585f6a4226" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RecordedUnconditionalPurchaseObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_RecordedUnconditionalPurchaseObligation_019e64ef-17ea-7e76-b172-41585f6a4226" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDeferredInvestmentTaxCredit_019e64ef-17ea-7940-a5f4-814ddb1bb16b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDeferredInvestmentTaxCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_AccumulatedDeferredInvestmentTaxCredit_019e64ef-17ea-7940-a5f4-814ddb1bb16b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_019e64ef-17ea-7595-96b0-18a1339087fb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_019e64ef-17ea-7595-96b0-18a1339087fb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019e64ef-17ea-73af-989c-186dafe8e5ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019e64ef-17ea-73af-989c-186dafe8e5ef" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019e64ef-17ea-7e87-bbf7-3ec030cac2d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019e64ef-17ea-7e87-bbf7-3ec030cac2d6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCreditsAndOtherLiabilities_019e64ef-17ea-7d38-9236-51d07b476bcf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCreditsAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_019e64ef-1730-714b-ba9e-b196cd920344" xlink:to="loc_us-gaap_DeferredCreditsAndOtherLiabilities_019e64ef-17ea-7d38-9236-51d07b476bcf" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019e64ef-17ea-7724-bbf0-4f0ad5aa326b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019e64ef-17ea-7724-bbf0-4f0ad5aa326b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValueOutstanding_019e64ef-17ea-793e-a9f4-e0f351c265dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValueOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_CommonStockValueOutstanding_019e64ef-17ea-793e-a9f4-e0f351c265dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019e64ef-17ea-7bb7-9853-b98e6155cc4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019e64ef-17ea-7bb7-9853-b98e6155cc4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e64ef-17ea-73a2-8b91-8307fffec3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e64ef-17ea-73a2-8b91-8307fffec3e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e64ef-17ea-7149-b63e-caa632802419" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e64ef-17ea-7149-b63e-caa632802419" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e64ef-17ea-7970-90ae-9c3327e2f4bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_StockholdersEquity_019e64ef-17ea-7970-90ae-9c3327e2f4bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_019e64ef-17ea-77b6-8fdf-8432447c1f9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_MinorityInterest_019e64ef-17ea-77b6-8fdf-8432447c1f9f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-17ea-7a37-b408-1cfb41c3bc70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-17ea-7a37-b408-1cfb41c3bc70" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019e64ef-17ea-77d7-a227-54750f5459f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019e64ef-17ea-77d7-a227-54750f5459f5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizationLongtermDebtAndEquity_019e64ef-17ea-7403-b717-8068c7fd260e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizationLongtermDebtAndEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e64ef-17ea-7687-b77c-90afd01687de" xlink:to="loc_us-gaap_CapitalizationLongtermDebtAndEquity_019e64ef-17ea-7403-b717-8068c7fd260e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e64ef-17ea-75fb-b881-e64cf16d21d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e64ef-1730-77be-8e11-0ae09fc685d3" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e64ef-17ea-75fb-b881-e64cf16d21d0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="simple" xlink:href="pnw-20260630.xsd#ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-17ea-7ad2-870c-e54ad72ef083" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:to="loc_us-gaap_StatementTable_019e64ef-17ea-7ad2-870c-e54ad72ef083" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-75d9-9319-00c63c815945" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-17ea-7ad2-870c-e54ad72ef083" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-75d9-9319-00c63c815945" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-75d9-9319-00c63c815945_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-75d9-9319-00c63c815945" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-75d9-9319-00c63c815945_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-72ec-b013-1864f22dc58f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-75d9-9319-00c63c815945" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-72ec-b013-1864f22dc58f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-72b3-bdcf-961eb0d8a7bc" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-72ec-b013-1864f22dc58f" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-72b3-bdcf-961eb0d8a7bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-752b-a120-813a42a62c63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-752b-a120-813a42a62c63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e64ef-17ea-7a2d-8b60-dd73978c3c18" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-752b-a120-813a42a62c63" xlink:to="loc_us-gaap_ProfitLoss_019e64ef-17ea-7a2d-8b60-dd73978c3c18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-752b-a120-813a42a62c63" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019e64ef-17ea-743e-a5c1-22746fb5b4d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019e64ef-17ea-743e-a5c1-22746fb5b4d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019e64ef-17ea-7f20-b8e9-4e4860ea228f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019e64ef-17ea-7f20-b8e9-4e4860ea228f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_019e64ef-17ea-76b1-882c-66d45529dab8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_019e64ef-17ea-76b1-882c-66d45529dab8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredInvestmentTaxCreditExpense_019e64ef-17ea-7099-8697-8ea2eae93da4" xlink:href="pnw-20260630.xsd#pnw_DeferredInvestmentTaxCreditExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_pnw_DeferredInvestmentTaxCreditExpense_019e64ef-17ea-7099-8697-8ea2eae93da4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable_019e64ef-17ea-7377-a022-74416101fc2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable_019e64ef-17ea-7377-a022-74416101fc2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_019e64ef-17ea-70a2-b98b-68e1a1729090" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_019e64ef-17ea-70a2-b98b-68e1a1729090" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_019e64ef-17ea-7208-a6e2-14091373256a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_019e64ef-17ea-7208-a6e2-14091373256a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue_019e64ef-17ea-7841-8bf6-cc03f98e2bb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue_019e64ef-17ea-7841-8bf6-cc03f98e2bb9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization_019e64ef-17ea-70ec-91d5-1fa790c784b1" xlink:href="pnw-20260630.xsd#pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization_019e64ef-17ea-70ec-91d5-1fa790c784b1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncomeTaxesReceivable_019e64ef-17ea-7745-a0a6-9c675c6053f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInIncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInIncomeTaxesReceivable_019e64ef-17ea-7745-a0a6-9c675c6053f4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidExpense_019e64ef-17ea-7798-824d-f58194b3de47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidExpense_019e64ef-17ea-7798-824d-f58194b3de47" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_019e64ef-17ea-79d5-8bca-4fc9c98b1c4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_019e64ef-17ea-79d5-8bca-4fc9c98b1c4a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedTaxesPayable_019e64ef-17ea-78ba-824f-c20e719109a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccruedTaxesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedTaxesPayable_019e64ef-17ea-78ba-824f-c20e719109a2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherAccruedLiabilities_019e64ef-17ea-7209-b8a2-2b1e0f526b7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019e64ef-17ea-7744-9096-35639b4ffb30" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherAccruedLiabilities_019e64ef-17ea-7209-b8a2-2b1e0f526b7e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherRegulatoryAssets_019e64ef-17ea-7cab-a972-d6d12f0b2762" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherRegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherRegulatoryAssets_019e64ef-17ea-7cab-a972-d6d12f0b2762" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRegulatoryLiabilities_019e64ef-17ea-79c4-b0fa-7c43858bf0c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInRegulatoryLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_IncreaseDecreaseInRegulatoryLiabilities_019e64ef-17ea-79c4-b0fa-7c43858bf0c1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_019e64ef-17ea-7c09-b630-a183182addc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_019e64ef-17ea-7c09-b630-a183182addc2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncreaseDecreaseInOperatingLeaseRightOfUseAsset_019e64ef-17ea-79d4-9b11-041fc01ea3f9" xlink:href="pnw-20260630.xsd#pnw_IncreaseDecreaseInOperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_pnw_IncreaseDecreaseInOperatingLeaseRightOfUseAsset_019e64ef-17ea-79d4-9b11-041fc01ea3f9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_019e64ef-17ea-78f3-9ae4-6e5ce14d209e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_019e64ef-17ea-78f3-9ae4-6e5ce14d209e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_019e64ef-17ea-7322-87b2-ee10eafe1be4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-7b03-959f-1d79fb5f2004" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_019e64ef-17ea-7322-87b2-ee10eafe1be4" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e64ef-17ea-7451-a1e2-10cd213db546" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e64ef-17ea-752b-a120-813a42a62c63" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e64ef-17ea-7451-a1e2-10cd213db546" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_019e64ef-17ea-73f0-95fe-7f2848c7413a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_019e64ef-17ea-73f0-95fe-7f2848c7413a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromContributionInAidOfConstruction_019e64ef-17ea-725d-9187-09123dd40732" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromContributionInAidOfConstruction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_us-gaap_ProceedsFromContributionInAidOfConstruction_019e64ef-17ea-725d-9187-09123dd40732" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForFundsUsedDuringConstructionInvestingActivities_019e64ef-17ea-7e43-b343-199931866d06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForFundsUsedDuringConstructionInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_us-gaap_AllowanceForFundsUsedDuringConstructionInvestingActivities_019e64ef-17ea-7e43-b343-199931866d06" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ProceedsFromDecommissioningTrustFundAssetsAndOtherSpecialUseFunds_019e64ef-17ea-783a-8a66-103b01ef1a70" xlink:href="pnw-20260630.xsd#pnw_ProceedsFromDecommissioningTrustFundAssetsAndOtherSpecialUseFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_pnw_ProceedsFromDecommissioningTrustFundAssetsAndOtherSpecialUseFunds_019e64ef-17ea-783a-8a66-103b01ef1a70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PaymentsToAcquireInvestmentsToBeHeldInDecommissioningTrustFundAndOtherSpecialUseFunds_019e64ef-17ea-7026-a9b6-ec3089db5731" xlink:href="pnw-20260630.xsd#pnw_PaymentsToAcquireInvestmentsToBeHeldInDecommissioningTrustFundAndOtherSpecialUseFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_pnw_PaymentsToAcquireInvestmentsToBeHeldInDecommissioningTrustFundAndOtherSpecialUseFunds_019e64ef-17ea-7026-a9b6-ec3089db5731" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_019e64ef-17ea-7504-9f67-5c79383b1a95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_019e64ef-17ea-7504-9f67-5c79383b1a95" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e64ef-17ea-7ce0-9295-5e79f5b80f9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e64ef-17ea-71b1-90a0-9e717988f40a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e64ef-17ea-7ce0-9295-5e79f5b80f9d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfOtherLongTermDebt_019e64ef-17ea-7ca5-a0b2-ef387b458ed3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfOtherLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfOtherLongTermDebt_019e64ef-17ea-7ca5-a0b2-ef387b458ed3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfOtherLongTermDebt_019f608e-1738-73fc-a26b-34fa2a71d288" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfOtherLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_RepaymentsOfOtherLongTermDebt_019f608e-1738-73fc-a26b-34fa2a71d288" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ProceedsFromRepaymentsOfShortTermDebtNet_019e64ef-17ea-773b-867a-6f3c6de8b238" xlink:href="pnw-20260630.xsd#pnw_ProceedsFromRepaymentsOfShortTermDebtNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_pnw_ProceedsFromRepaymentsOfShortTermDebtNet_019e64ef-17ea-773b-867a-6f3c6de8b238" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSecuredDebt_019f608e-e496-7c44-9437-6b28f634536a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSecuredDebt_019f608e-e496-7c44-9437-6b28f634536a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromContributionsFromParent_019f608e-e496-71d3-9640-09468c8774bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromContributionsFromParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_ProceedsFromContributionsFromParent_019f608e-e496-71d3-9640-09468c8774bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_019e64ef-17ea-72a1-abe8-6f6758379ed7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_019e64ef-17ea-72a1-abe8-6f6758379ed7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToMinorityShareholders_019f608f-13aa-79b7-9912-7e2f594a058f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToMinorityShareholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_PaymentsToMinorityShareholders_019f608f-13aa-79b7-9912-7e2f594a058f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e64ef-17ea-7143-956e-077ea50cdebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e64ef-17ea-7c47-8832-e19bf39df957" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e64ef-17ea-7143-956e-077ea50cdebf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e64ef-17ea-7258-95d6-1641d7467c7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e64ef-17ea-7258-95d6-1641d7467c7c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019e64ef-17ea-7732-8535-7398c7922f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75a8-99c6-df6bf99f1533" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019e64ef-17ea-7732-8535-7398c7922f6c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019e64ef-17ea-7734-be29-6e5a260e7a63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY" xlink:type="simple" xlink:href="pnw-20260630.xsd#ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ARIZONAPUBLICSERVICECOMPANYCONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e64ef-17ea-75ab-9693-2ffbddae9206" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e64ef-17ea-7840-b8fa-76cb56825430" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75ab-9693-2ffbddae9206" xlink:to="loc_us-gaap_StatementTable_019e64ef-17ea-7840-b8fa-76cb56825430" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-75ae-839b-cdc2b5ec236a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-17ea-7840-b8fa-76cb56825430" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-75ae-839b-cdc2b5ec236a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-75ae-839b-cdc2b5ec236a_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-75ae-839b-cdc2b5ec236a" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-75ae-839b-cdc2b5ec236a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-73e8-bf28-09e4598e8fad" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-75ae-839b-cdc2b5ec236a" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-73e8-bf28-09e4598e8fad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7e85-9fb1-a566b4295946" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-73e8-bf28-09e4598e8fad" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7e85-9fb1-a566b4295946" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-17ea-71ba-aea2-1693a910f428" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e64ef-17ea-7840-b8fa-76cb56825430" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-17ea-71ba-aea2-1693a910f428" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-71ba-aea2-1693a910f428_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-17ea-71ba-aea2-1693a910f428" xlink:to="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-71ba-aea2-1693a910f428_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-17ea-71ba-aea2-1693a910f428" xlink:to="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e64ef-17ea-735b-b78e-4a9a4d0e65e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:to="loc_us-gaap_CommonStockMember_019e64ef-17ea-735b-b78e-4a9a4d0e65e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019e64ef-17ea-7801-beb3-1e941f2b9dde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019e64ef-17ea-7801-beb3-1e941f2b9dde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e64ef-17ea-7548-9a1f-cda8d81980a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:to="loc_us-gaap_RetainedEarningsMember_019e64ef-17ea-7548-9a1f-cda8d81980a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-17ea-751b-80fb-e8a9a7652937" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-17ea-751b-80fb-e8a9a7652937" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019e64ef-17ea-752d-bc29-333c400eb29d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-17ea-7f65-9674-1516bb16e469" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019e64ef-17ea-752d-bc29-333c400eb29d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e64ef-17ea-75ab-9693-2ffbddae9206" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019e64ef-17ea-76a8-bee8-e4cc54afc205" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_CommonStockSharesIssued_019e64ef-17ea-76a8-bee8-e4cc54afc205" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-17ea-736a-9d76-388fc4ac5529" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-17ea-736a-9d76-388fc4ac5529" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AdjustmentsToAdditionalPaidInCapitalContributionsFromParent_019ecb7c-5b25-76f5-aed5-656ad745998c" xlink:href="pnw-20260630.xsd#pnw_AdjustmentsToAdditionalPaidInCapitalContributionsFromParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_pnw_AdjustmentsToAdditionalPaidInCapitalContributionsFromParent_019ecb7c-5b25-76f5-aed5-656ad745998c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e64ef-17ea-7131-9a8c-b9819d1d7f50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_ProfitLoss_019e64ef-17ea-7131-9a8c-b9819d1d7f50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e64ef-17ea-77c9-a491-2ca34d7010d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e64ef-17ea-77c9-a491-2ca34d7010d7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_019ecb7c-5b25-7e81-ac8b-f2e8b3c8f805" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_DividendsCommonStockCash_019ecb7c-5b25-7e81-ac8b-f2e8b3c8f805" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_019ecb7c-5b25-7287-9fee-de35fd592735" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_019ecb7c-5b25-7287-9fee-de35fd592735" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_019e64ef-17ea-7dd3-ba7d-ce69fa627204" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e64ef-17ea-7412-95bc-5326c084521b" xlink:to="loc_us-gaap_StockholdersEquityOther_019e64ef-17ea-7dd3-ba7d-ce69fa627204" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019e64ef-17ea-7691-bec5-8a97252d7e5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-17ea-7218-bca0-11024ad36ec4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ConsolidationandNatureofOperationsAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#ConsolidationandNatureofOperationsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ConsolidationandNatureofOperationsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilityPropertyPlantAndEquipmentLineItems_019e64ef-17ea-7c3d-ad47-df10c8180213" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilityPropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7ae6-bed1-4d0492714859" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PublicUtilityPropertyPlantAndEquipmentLineItems_019e64ef-17ea-7c3d-ad47-df10c8180213" xlink:to="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7ae6-bed1-4d0492714859" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-77dc-9b85-31a6d3324493" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7ae6-bed1-4d0492714859" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-77dc-9b85-31a6d3324493" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-77dc-9b85-31a6d3324493_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-77dc-9b85-31a6d3324493" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-77dc-9b85-31a6d3324493_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7be0-bdc8-d0c940a46ac8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-77dc-9b85-31a6d3324493" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7be0-bdc8-d0c940a46ac8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-17ea-7299-a81f-3472bca163e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7be0-bdc8-d0c940a46ac8" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-17ea-7299-a81f-3472bca163e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7c40-b5a0-68bb01db3fa0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7ae6-bed1-4d0492714859" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7c40-b5a0-68bb01db3fa0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7c40-b5a0-68bb01db3fa0_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7c40-b5a0-68bb01db3fa0" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7c40-b5a0-68bb01db3fa0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-749e-9a02-02e41f065bef" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7c40-b5a0-68bb01db3fa0" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-749e-9a02-02e41f065bef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-73f3-8899-a643e7403234" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-749e-9a02-02e41f065bef" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-73f3-8899-a643e7403234" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVIELessorTrustsAcquired_019e64ef-17ea-7d86-b016-2c3e290c04d0" xlink:href="pnw-20260630.xsd#pnw_NumberOfVIELessorTrustsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilityPropertyPlantAndEquipmentLineItems_019e64ef-17ea-7c3d-ad47-df10c8180213" xlink:to="loc_pnw_NumberOfVIELessorTrustsAcquired_019e64ef-17ea-7d86-b016-2c3e290c04d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVieLessorTrusts_019e64ef-17ea-715c-84c8-60d57768f328" xlink:href="pnw-20260630.xsd#pnw_NumberOfVieLessorTrusts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilityPropertyPlantAndEquipmentLineItems_019e64ef-17ea-7c3d-ad47-df10c8180213" xlink:to="loc_pnw_NumberOfVieLessorTrusts_019e64ef-17ea-715c-84c8-60d57768f328" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ConsolidationandNatureofOperationsScheduleofSupplementalCashFlowInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#ConsolidationandNatureofOperationsScheduleofSupplementalCashFlowInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ConsolidationandNatureofOperationsScheduleofSupplementalCashFlowInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsLineItems_019e64ef-17ea-7723-aa2d-3a3fe970bebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_019e64ef-17ea-79d0-9f24-ec19ebaf46b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCashAndCashEquivalentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_019e64ef-17ea-7723-aa2d-3a3fe970bebf" xlink:to="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_019e64ef-17ea-79d0-9f24-ec19ebaf46b4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7532-a855-adbb1be4c694" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_019e64ef-17ea-79d0-9f24-ec19ebaf46b4" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7532-a855-adbb1be4c694" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7532-a855-adbb1be4c694_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7532-a855-adbb1be4c694" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7532-a855-adbb1be4c694_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-78d1-9fcf-a4edfac3da76" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7532-a855-adbb1be4c694" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-78d1-9fcf-a4edfac3da76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7847-8d3a-4f2199faa326" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-78d1-9fcf-a4edfac3da76" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7847-8d3a-4f2199faa326" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionAbstract_019f65e1-3fc7-7068-8b36-62338c242c12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxPaidByIndividualJurisdictionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_019e64ef-17ea-7723-aa2d-3a3fe970bebf" xlink:to="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionAbstract_019f65e1-3fc7-7068-8b36-62338c242c12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019e64ef-17ea-7f46-9df3-6019353167db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionAbstract_019f65e1-3fc7-7068-8b36-62338c242c12" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019e64ef-17ea-7f46-9df3-6019353167db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_019e64ef-17ea-7ef6-bc2b-4c43827f6c22" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionAbstract_019f65e1-3fc7-7068-8b36-62338c242c12" xlink:to="loc_us-gaap_InterestPaidNet_019e64ef-17ea-7ef6-bc2b-4c43827f6c22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019e64ef-17ea-7182-9bac-8396c90577af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_019e64ef-17ea-7723-aa2d-3a3fe970bebf" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019e64ef-17ea-7182-9bac-8396c90577af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_019e64ef-17ea-7cfb-bf8a-9de57646e970" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019e64ef-17ea-7182-9bac-8396c90577af" xlink:to="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_019e64ef-17ea-7cfb-bf8a-9de57646e970" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_019eed01-6bf5-787a-b243-8c21c05dba83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019e64ef-17ea-7182-9bac-8396c90577af" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_019eed01-6bf5-787a-b243-8c21c05dba83" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/BusinessSegmentsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#BusinessSegmentsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/BusinessSegmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019e64ef-17ea-792b-bf97-70005bfd0a12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019e64ef-17ea-792b-bf97-70005bfd0a12" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e64ef-17ea-7aaa-81fb-b5628c63d6df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019e64ef-17ea-792b-bf97-70005bfd0a12" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e64ef-17ea-7aaa-81fb-b5628c63d6df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e64ef-17ea-7aaa-81fb-b5628c63d6df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e64ef-17ea-7aaa-81fb-b5628c63d6df" xlink:to="loc_us-gaap_SegmentDomain_019e64ef-17ea-7aaa-81fb-b5628c63d6df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e64ef-17ea-744f-85ae-21cff2ae010f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e64ef-17ea-7aaa-81fb-b5628c63d6df" xlink:to="loc_us-gaap_SegmentDomain_019e64ef-17ea-744f-85ae-21cff2ae010f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ReportableSegmentMember_019e64ef-17ea-7e6b-acf1-da1db9c35a7d" xlink:href="pnw-20260630.xsd#pnw_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e64ef-17ea-744f-85ae-21cff2ae010f" xlink:to="loc_pnw_ReportableSegmentMember_019e64ef-17ea-7e6b-acf1-da1db9c35a7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember_019e64ef-17ea-7960-bc82-51dadfcfa9bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ReportableSegmentMember_019e64ef-17ea-7e6b-acf1-da1db9c35a7d" xlink:to="loc_us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember_019e64ef-17ea-7960-bc82-51dadfcfa9bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateAndOtherMember_019e64ef-17ea-7f75-9922-eaec225c6a6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ReportableSegmentMember_019e64ef-17ea-7e6b-acf1-da1db9c35a7d" xlink:to="loc_us-gaap_CorporateAndOtherMember_019e64ef-17ea-7f75-9922-eaec225c6a6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7059-a77f-0588bc22fc89" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019e64ef-17ea-792b-bf97-70005bfd0a12" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7059-a77f-0588bc22fc89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7059-a77f-0588bc22fc89_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7059-a77f-0588bc22fc89" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7059-a77f-0588bc22fc89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7d06-927e-9ed41765dc15" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7059-a77f-0588bc22fc89" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7d06-927e-9ed41765dc15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_019e64ef-17ea-7299-a43e-4361314cf01b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7d06-927e-9ed41765dc15" xlink:to="loc_srt_ParentCompanyMember_019e64ef-17ea-7299-a43e-4361314cf01b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019e64ef-17ea-755f-aad2-4b1dfc1a2dca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_NumberOfReportableSegments_019e64ef-17ea-755f-aad2-4b1dfc1a2dca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e64ef-17ea-7da5-8448-598f8701dd7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_Revenues_019e64ef-17ea-7da5-8448-598f8701dd7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e64ef-17ea-76e3-a5b2-1edd4533ced6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e64ef-17ea-76e3-a5b2-1edd4533ced6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations_019e64ef-17ea-7d9d-9477-42dc9f87a03d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations_019e64ef-17ea-7d9d-9477-42dc9f87a03d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSoldDepreciationAndAmortization_019e64ef-17ea-7a08-8834-671629e065de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSoldDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSoldDepreciationAndAmortization_019e64ef-17ea-7a08-8834-671629e065de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesExcludingIncomeAndExciseTaxes_019e64ef-17ea-7624-ad7d-cc777833fe35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxesExcludingIncomeAndExciseTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_TaxesExcludingIncomeAndExciseTaxes_019e64ef-17ea-7624-ad7d-cc777833fe35" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019e64ef-17ea-7184-8369-59c277b89e5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019e64ef-17ea-7184-8369-59c277b89e5c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019e64ef-17ea-7979-aa6c-edc9cd8964ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionAndOtherPostretirementBenefitExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019e64ef-17ea-7979-aa6c-edc9cd8964ba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019e64ef-17ea-76a7-9508-a8ee10a3c3c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019e64ef-17ea-76a7-9508-a8ee10a3c3c9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e64ef-17ea-72f8-9099-7c3d7de598f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e64ef-17ea-72f8-9099-7c3d7de598f1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e64ef-17ea-7d00-8449-32fbf47aca14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e64ef-17ea-7d00-8449-32fbf47aca14" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-17ea-7c0c-8460-fdb6da76b809" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-17ea-7c0c-8460-fdb6da76b809" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e64ef-17ea-7c30-aabb-b4a3a7d21a66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e64ef-17ea-7c30-aabb-b4a3a7d21a66" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e64ef-17ea-728a-b51d-8d371343c9f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019e64ef-17ea-7b48-b15c-ae9ce45eff87" xlink:to="loc_us-gaap_Assets_019e64ef-17ea-728a-b51d-8d371343c9f9" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RevenueScheduleofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RevenueScheduleofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RevenueScheduleofDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-7afc-b537-31a54fe242ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-7201-8aa8-685d875326b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-7afc-b537-31a54fe242ea" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-7201-8aa8-685d875326b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019e64ef-17ea-7f6a-aa79-5d5f5937d645" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-7201-8aa8-685d875326b0" xlink:to="loc_srt_MajorCustomersAxis_019e64ef-17ea-7f6a-aa79-5d5f5937d645" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e64ef-17ea-7f6a-aa79-5d5f5937d645_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019e64ef-17ea-7f6a-aa79-5d5f5937d645" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e64ef-17ea-7f6a-aa79-5d5f5937d645_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e64ef-17ea-7ad4-b3d4-6cbe2179a6f1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019e64ef-17ea-7f6a-aa79-5d5f5937d645" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e64ef-17ea-7ad4-b3d4-6cbe2179a6f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RetailResidentialMember_019e64ef-17ea-7da4-ab27-6d6edcd902e0" xlink:href="pnw-20260630.xsd#pnw_RetailResidentialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e64ef-17ea-7ad4-b3d4-6cbe2179a6f1" xlink:to="loc_pnw_RetailResidentialMember_019e64ef-17ea-7da4-ab27-6d6edcd902e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RetailNonResidentialMember_019e64ef-17ea-7a5b-969f-435a9c6f4812" xlink:href="pnw-20260630.xsd#pnw_RetailNonResidentialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e64ef-17ea-7ad4-b3d4-6cbe2179a6f1" xlink:to="loc_pnw_RetailNonResidentialMember_019e64ef-17ea-7a5b-969f-435a9c6f4812" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7e08-aac6-bc125a590a24" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-7201-8aa8-685d875326b0" xlink:to="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7e08-aac6-bc125a590a24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7e08-aac6-bc125a590a24_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7e08-aac6-bc125a590a24" xlink:to="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7e08-aac6-bc125a590a24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7918-9852-8b911d821435" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7e08-aac6-bc125a590a24" xlink:to="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7918-9852-8b911d821435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RetailElectricServiceMember_019e64ef-17ea-71aa-b1b9-96cd2c3f61dd" xlink:href="pnw-20260630.xsd#pnw_RetailElectricServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7918-9852-8b911d821435" xlink:to="loc_pnw_RetailElectricServiceMember_019e64ef-17ea-71aa-b1b9-96cd2c3f61dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_WholesaleMember_019e64ef-17ea-7c2c-a8bf-cb900c3209e1" xlink:href="pnw-20260630.xsd#pnw_WholesaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7918-9852-8b911d821435" xlink:to="loc_pnw_WholesaleMember_019e64ef-17ea-7c2c-a8bf-cb900c3209e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TransmissionServicesMember_019e64ef-17ea-70b8-8a56-29803bd7156e" xlink:href="pnw-20260630.xsd#pnw_TransmissionServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7918-9852-8b911d821435" xlink:to="loc_pnw_TransmissionServicesMember_019e64ef-17ea-70b8-8a56-29803bd7156e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OtherServicesMember_019e64ef-17ea-79e2-8ea8-9da0cde47346" xlink:href="pnw-20260630.xsd#pnw_OtherServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7918-9852-8b911d821435" xlink:to="loc_pnw_OtherServicesMember_019e64ef-17ea-79e2-8ea8-9da0cde47346" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e64ef-17ea-7a9a-aac3-e66892ac0ffd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-7afc-b537-31a54fe242ea" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e64ef-17ea-7a9a-aac3-e66892ac0ffd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RevenueAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RevenueAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RevenueAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-72d4-97c8-779ca8593a77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-74b1-a6a1-26018f752c8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-72d4-97c8-779ca8593a77" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-74b1-a6a1-26018f752c8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7d1d-b612-ed17ce01ecf0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e64ef-17ea-74b1-a6a1-26018f752c8a" xlink:to="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7d1d-b612-ed17ce01ecf0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7d1d-b612-ed17ce01ecf0_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7d1d-b612-ed17ce01ecf0" xlink:to="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-7d1d-b612-ed17ce01ecf0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-707f-b2ca-aeafeea43dc5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e64ef-17ea-7d1d-b612-ed17ce01ecf0" xlink:to="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-707f-b2ca-aeafeea43dc5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RetailElectricServiceMember_019e64ef-17ea-7c54-9f8d-c24e9c3a0c4b" xlink:href="pnw-20260630.xsd#pnw_RetailElectricServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-707f-b2ca-aeafeea43dc5" xlink:to="loc_pnw_RetailElectricServiceMember_019e64ef-17ea-7c54-9f8d-c24e9c3a0c4b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ElectricandTransmissionServiceMember_019f830e-a7c7-7cec-9ee1-d7611cd074de" xlink:href="pnw-20260630.xsd#pnw_ElectricandTransmissionServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e64ef-17ea-707f-b2ca-aeafeea43dc5" xlink:to="loc_pnw_ElectricandTransmissionServiceMember_019f830e-a7c7-7cec-9ee1-d7611cd074de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RevenueFromContractWithCustomerPaymentTerms_019e64ef-17ea-7a30-98e9-7f479a2ecbd3" xlink:href="pnw-20260630.xsd#pnw_RevenueFromContractWithCustomerPaymentTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-72d4-97c8-779ca8593a77" xlink:to="loc_pnw_RevenueFromContractWithCustomerPaymentTerms_019e64ef-17ea-7a30-98e9-7f479a2ecbd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e64ef-17ea-7062-b87f-f8e8f2d631cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-72d4-97c8-779ca8593a77" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e64ef-17ea-7062-b87f-f8e8f2d631cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryCostRecoveryRevenue_019e64ef-17ea-7f4b-b0b8-119999f9a85d" xlink:href="pnw-20260630.xsd#pnw_RegulatoryCostRecoveryRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e64ef-17ea-72d4-97c8-779ca8593a77" xlink:to="loc_pnw_RegulatoryCostRecoveryRevenue_019e64ef-17ea-7f4b-b0b8-119999f9a85d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_019e64ef-17ea-7b0a-b96a-3ab92e94a3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_019e64ef-17ea-708d-8630-0ed8cf2cacda" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019e64ef-17ea-7b0a-b96a-3ab92e94a3e8" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_019e64ef-17ea-708d-8630-0ed8cf2cacda" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodAxis_019e64ef-17ea-78ae-ab42-aaa0e8984043" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_019e64ef-17ea-708d-8630-0ed8cf2cacda" xlink:to="loc_us-gaap_TaxPeriodAxis_019e64ef-17ea-78ae-ab42-aaa0e8984043" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-78ae-ab42-aaa0e8984043_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_019e64ef-17ea-78ae-ab42-aaa0e8984043" xlink:to="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-78ae-ab42-aaa0e8984043_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-7422-ac93-a5a04838657b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_019e64ef-17ea-78ae-ab42-aaa0e8984043" xlink:to="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-7422-ac93-a5a04838657b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxYear2024Member_019e64ef-17ea-7e7f-88db-b364d46ad598" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxYear2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-7422-ac93-a5a04838657b" xlink:to="loc_us-gaap_TaxYear2024Member_019e64ef-17ea-7e7f-88db-b364d46ad598" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxYear2025Member_019e64ef-17ea-7b15-9e69-3252bb9dcdcd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxYear2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-7422-ac93-a5a04838657b" xlink:to="loc_us-gaap_TaxYear2025Member_019e64ef-17ea-7b15-9e69-3252bb9dcdcd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxYear2026Member_019f609e-b805-723d-8c19-b4bed748d3ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxYear2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_019e64ef-17ea-7422-ac93-a5a04838657b" xlink:to="loc_us-gaap_TaxYear2026Member_019f609e-b805-723d-8c19-b4bed748d3ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f609f-00b4-7b57-b983-583247bdf08e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_019e64ef-17ea-708d-8630-0ed8cf2cacda" xlink:to="loc_srt_RangeAxis_019f609f-00b4-7b57-b983-583247bdf08e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f609f-00b4-7b57-b983-583247bdf08e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f609f-00b4-7b57-b983-583247bdf08e" xlink:to="loc_srt_RangeMember_019f609f-00b4-7b57-b983-583247bdf08e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f609f-00b4-7bf3-ad47-93d0baf6565c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f609f-00b4-7b57-b983-583247bdf08e" xlink:to="loc_srt_RangeMember_019f609f-00b4-7bf3-ad47-93d0baf6565c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f609f-26e3-7ae6-a6a6-3852295f7756" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f609f-00b4-7bf3-ad47-93d0baf6565c" xlink:to="loc_srt_MinimumMember_019f609f-26e3-7ae6-a6a6-3852295f7756" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f609f-590b-71a8-b56d-d80dbecea788" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f609f-00b4-7bf3-ad47-93d0baf6565c" xlink:to="loc_srt_MaximumMember_019f609f-590b-71a8-b56d-d80dbecea788" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount_019e64ef-17ea-7afd-a524-e3e043d211a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019e64ef-17ea-7b0a-b96a-3ab92e94a3e8" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount_019e64ef-17ea-7afd-a524-e3e043d211a5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DebtandLiquidityMattersAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DebtandLiquidityMattersAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DebtandLiquidityMattersAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7988-9ea2-cb38e77440f6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7988-9ea2-cb38e77440f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7988-9ea2-cb38e77440f6_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7988-9ea2-cb38e77440f6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7988-9ea2-cb38e77440f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-70ed-8ca3-21218aba0ad1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7988-9ea2-cb38e77440f6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-70ed-8ca3-21218aba0ad1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_019e64ef-17ea-7c56-8adf-1686ad330a82" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-70ed-8ca3-21218aba0ad1" xlink:to="loc_srt_ParentCompanyMember_019e64ef-17ea-7c56-8adf-1686ad330a82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e64ef-17ea-7368-8680-f94082a31d1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_us-gaap_CreditFacilityAxis_019e64ef-17ea-7368-8680-f94082a31d1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7368-8680-f94082a31d1b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e64ef-17ea-7368-8680-f94082a31d1b" xlink:to="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7368-8680-f94082a31d1b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7d94-8f9a-4cc90ded0b0f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e64ef-17ea-7368-8680-f94082a31d1b" xlink:to="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7d94-8f9a-4cc90ded0b0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e64ef-17ea-74b7-b4fe-f1fe770ad8eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7d94-8f9a-4cc90ded0b0f" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e64ef-17ea-74b7-b4fe-f1fe770ad8eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019e64ef-17ea-7320-bd16-06d48f77f544" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7d94-8f9a-4cc90ded0b0f" xlink:to="loc_us-gaap_LetterOfCreditMember_019e64ef-17ea-7320-bd16-06d48f77f544" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019e64ef-17ea-79f8-8d04-bbb71909c2c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e64ef-17ea-7d94-8f9a-4cc90ded0b0f" xlink:to="loc_us-gaap_CommercialPaperMember_019e64ef-17ea-79f8-8d04-bbb71909c2c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e64ef-17ea-7ee9-8415-f7c7a8e2cf72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e64ef-17ea-7ee9-8415-f7c7a8e2cf72" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-7ee9-8415-f7c7a8e2cf72_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e64ef-17ea-7ee9-8415-f7c7a8e2cf72" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-7ee9-8415-f7c7a8e2cf72_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e64ef-17ea-7ee9-8415-f7c7a8e2cf72" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RevolvingCreditFacilityMaturingApril2029Member_019e64ef-17ea-7545-9d1f-7e3471b144c0" xlink:href="pnw-20260630.xsd#pnw_RevolvingCreditFacilityMaturingApril2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:to="loc_pnw_RevolvingCreditFacilityMaturingApril2029Member_019e64ef-17ea-7545-9d1f-7e3471b144c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TermLoanFacilityMaturingDecember32026Member_019e64ef-17ea-731a-87e2-8210cdfd8f96" xlink:href="pnw-20260630.xsd#pnw_TermLoanFacilityMaturingDecember32026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:to="loc_pnw_TermLoanFacilityMaturingDecember32026Member_019e64ef-17ea-731a-87e2-8210cdfd8f96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_A4.65SeniorUnsecuredNotedMaturingJune2029Member_019ed13b-a288-700b-bebc-50f9d2073328" xlink:href="pnw-20260630.xsd#pnw_A4.65SeniorUnsecuredNotedMaturingJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:to="loc_pnw_A4.65SeniorUnsecuredNotedMaturingJune2029Member_019ed13b-a288-700b-bebc-50f9d2073328" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SeniorUnsecuredNotesMaturingJune2026Member_019ed13d-d7c2-7b44-b3cd-c932b0807e6c" xlink:href="pnw-20260630.xsd#pnw_SeniorUnsecuredNotesMaturingJune2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:to="loc_pnw_SeniorUnsecuredNotesMaturingJune2026Member_019ed13d-d7c2-7b44-b3cd-c932b0807e6c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SeniorUnsecuredNotesMaturingMarch2036Member_019e64ef-17ea-795e-b1e3-709542645dd7" xlink:href="pnw-20260630.xsd#pnw_SeniorUnsecuredNotesMaturingMarch2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-17ea-76e0-bbf3-7c8bf79bb62c" xlink:to="loc_pnw_SeniorUnsecuredNotesMaturingMarch2036Member_019e64ef-17ea-795e-b1e3-709542645dd7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-72f2-b33b-8ddf531d73d5" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-72f2-b33b-8ddf531d73d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-72f2-b33b-8ddf531d73d5_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-72f2-b33b-8ddf531d73d5" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-72f2-b33b-8ddf531d73d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7a29-b46a-d2112693dd75" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-72f2-b33b-8ddf531d73d5" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7a29-b46a-d2112693dd75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7d02-b60a-d142db0f8b3a" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-7a29-b46a-d2112693dd75" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7d02-b60a-d142db0f8b3a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-17ea-76b5-bde4-079dc0ba2adf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-17ea-76b5-bde4-079dc0ba2adf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-17ea-76b5-bde4-079dc0ba2adf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-17ea-76b5-bde4-079dc0ba2adf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-17ea-76b5-bde4-079dc0ba2adf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-17ea-799a-92e6-55648be49de5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-17ea-76b5-bde4-079dc0ba2adf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-17ea-799a-92e6-55648be49de5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e64ef-17ea-7be4-af89-59ff2bf8f486" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-17ea-799a-92e6-55648be49de5" xlink:to="loc_us-gaap_SeniorNotesMember_019e64ef-17ea-7be4-af89-59ff2bf8f486" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019f8359-1d3f-75ce-97cf-3b0d86a0d828" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019f8359-1d3f-75ce-97cf-3b0d86a0d828" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019f8359-1d3f-75ce-97cf-3b0d86a0d828_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019f8359-1d3f-75ce-97cf-3b0d86a0d828" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019f8359-1d3f-75ce-97cf-3b0d86a0d828_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019f8359-1d3f-7a22-8806-83ef44c0e54e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019f8359-1d3f-75ce-97cf-3b0d86a0d828" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019f8359-1d3f-7a22-8806-83ef44c0e54e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019f8359-67fc-78d1-92cb-0f074630916f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019f8359-1d3f-7a22-8806-83ef44c0e54e" xlink:to="loc_us-gaap_CommercialPaperMember_019f8359-67fc-78d1-92cb-0f074630916f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019f8d34-f03a-7546-8064-c6a17f7eb4ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019f8d34-f03a-7546-8064-c6a17f7eb4ae" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019f8d34-f03a-7546-8064-c6a17f7eb4ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019f8d34-f03a-7546-8064-c6a17f7eb4ae" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019f8d34-f03a-7546-8064-c6a17f7eb4ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019f8d34-f03a-73e5-bf6d-c0803fbbe14f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019f8d34-f03a-7546-8064-c6a17f7eb4ae" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019f8d34-f03a-73e5-bf6d-c0803fbbe14f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019f8d35-10a8-7b12-892b-ab42724b81b6" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019f8d34-f03a-73e5-bf6d-c0803fbbe14f" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019f8d35-10a8-7b12-892b-ab42724b81b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f8d35-f89b-711e-a7fb-cee6d433314d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-77ef-bef8-682bbeef2143" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f8d35-f89b-711e-a7fb-cee6d433314d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f8d35-f89b-711e-a7fb-cee6d433314d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f8d35-f89b-711e-a7fb-cee6d433314d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f8d35-f89b-711e-a7fb-cee6d433314d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f8d35-f89b-70d1-abc8-bd0c65227989" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f8d35-f89b-711e-a7fb-cee6d433314d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f8d35-f89b-70d1-abc8-bd0c65227989" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f8d36-0990-74d2-b938-f8e58482a9fb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019f8d35-f89b-70d1-abc8-bd0c65227989" xlink:to="loc_us-gaap_SubsequentEventMember_019f8d36-0990-74d2-b938-f8e58482a9fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019e64ef-17ea-705d-8ccb-91a26f5b9b68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019e64ef-17ea-705d-8ccb-91a26f5b9b68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LineOfCreditFacilityAccordionFeatureIncreaseIncrement_019e64ef-17ea-7690-9a61-9a43dab545b5" xlink:href="pnw-20260630.xsd#pnw_LineOfCreditFacilityAccordionFeatureIncreaseIncrement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_LineOfCreditFacilityAccordionFeatureIncreaseIncrement_019e64ef-17ea-7690-9a61-9a43dab545b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LineOfCreditFacilityAccordionFeatureIncreaseLimit_019e64ef-17ea-7f7f-9eed-d84e0fa7d149" xlink:href="pnw-20260630.xsd#pnw_LineOfCreditFacilityAccordionFeatureIncreaseLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_LineOfCreditFacilityAccordionFeatureIncreaseLimit_019e64ef-17ea-7f7f-9eed-d84e0fa7d149" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e64ef-17ea-7b96-92cf-f9fc72fe93b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_LineOfCredit_019e64ef-17ea-7b96-92cf-f9fc72fe93b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019e64ef-17ea-7236-845c-29e5f6c2d87f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019e64ef-17ea-7236-845c-29e5f6c2d87f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaper_019e64ef-17ea-7678-a196-af2bd659a786" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaper"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_CommercialPaper_019e64ef-17ea-7678-a196-af2bd659a786" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_019e64ef-17ea-7633-976e-9dc0c4e3eb2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_019e64ef-17ea-7633-976e-9dc0c4e3eb2f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019e64ef-17ea-79c1-a829-4df2f2b8a701" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_DebtInstrumentTerm_019e64ef-17ea-79c1-a829-4df2f2b8a701" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019e64ef-17ea-7ce5-ab00-4ceed304b9f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019e64ef-17ea-7ce5-ab00-4ceed304b9f7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e64ef-17ea-753c-9e23-2e0fa685fce9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e64ef-17ea-753c-9e23-2e0fa685fce9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromShortTermDebt_019e64ef-17ea-7e91-b7e2-64130e13380c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromShortTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_ProceedsFromShortTermDebt_019e64ef-17ea-7e91-b7e2-64130e13380c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e64ef-17ea-7ac6-848f-2d70e009a9f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e64ef-17ea-7ac6-848f-2d70e009a9f1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSeniorDebt_019ed13c-c263-7361-b937-11a796b146a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_RepaymentsOfSeniorDebt_019ed13c-c263-7361-b937-11a796b146a6" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfShortTermDebt_019f8354-295b-7007-98e8-2f6db26f4514" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfShortTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_us-gaap_RepaymentsOfShortTermDebt_019f8354-295b-7007-98e8-2f6db26f4514" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LineOfCreditFacilityCommercialPaperProgramMaximumBorrowingCapacity_019e64ef-17ea-729c-80af-d590bac50be0" xlink:href="pnw-20260630.xsd#pnw_LineOfCreditFacilityCommercialPaperProgramMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_LineOfCreditFacilityCommercialPaperProgramMaximumBorrowingCapacity_019e64ef-17ea-729c-80af-d590bac50be0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AdjustmentsToAdditionalPaidInCapitalContributionsFromParent_019f16ed-3d04-7e0e-b350-e674b8ae93ef" xlink:href="pnw-20260630.xsd#pnw_AdjustmentsToAdditionalPaidInCapitalContributionsFromParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_AdjustmentsToAdditionalPaidInCapitalContributionsFromParent_019f16ed-3d04-7e0e-b350-e674b8ae93ef" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestToPermanentlyModifyPermittedYearlyEquityInfusionsPercentage_019e64ef-17ea-7e73-8ab7-a27c923f1071" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestToPermanentlyModifyPermittedYearlyEquityInfusionsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_PublicUtilitiesRequestToPermanentlyModifyPermittedYearlyEquityInfusionsPercentage_019e64ef-17ea-7e73-8ab7-a27c923f1071" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesApprovedEquityRatioAdditionalVariableRate_019e64ef-17ea-7356-a4f1-01d0ccbf4101" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesApprovedEquityRatioAdditionalVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_PublicUtilitiesApprovedEquityRatioAdditionalVariableRate_019e64ef-17ea-7356-a4f1-01d0ccbf4101" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilityOrderLongTermDebtAuthorization_019f8d34-3146-7282-9476-81b3f0610567" xlink:href="pnw-20260630.xsd#pnw_PublicUtilityOrderLongTermDebtAuthorization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-71f2-accf-f5341fcbc4b3" xlink:to="loc_pnw_PublicUtilityOrderLongTermDebtAuthorization_019f8d34-3146-7282-9476-81b3f0610567" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DebtandLiquidityMattersScheduleofEstimatedFairValueofLongTermDebtIncludingCurrentMaturitiesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DebtandLiquidityMattersScheduleofEstimatedFairValueofLongTermDebtIncludingCurrentMaturitiesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DebtandLiquidityMattersScheduleofEstimatedFairValueofLongTermDebtIncludingCurrentMaturitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-7418-a39b-05b77229c059" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-76f0-a034-8915bc83600b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-7418-a39b-05b77229c059" xlink:to="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-76f0-a034-8915bc83600b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7d7a-9fcc-f650b46af2d1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-76f0-a034-8915bc83600b" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7d7a-9fcc-f650b46af2d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7d7a-9fcc-f650b46af2d1_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7d7a-9fcc-f650b46af2d1" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7d7a-9fcc-f650b46af2d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7357-ae6e-90e48d351fa1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-17ea-7d7a-9fcc-f650b46af2d1" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7357-ae6e-90e48d351fa1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_019e64ef-17ea-7d9c-820b-8767921e7052" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-17ea-7357-ae6e-90e48d351fa1" xlink:to="loc_srt_ParentCompanyMember_019e64ef-17ea-7d9c-820b-8767921e7052" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7339-b97a-d97ccf6794bf" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e64ef-17ea-76f0-a034-8915bc83600b" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7339-b97a-d97ccf6794bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7339-b97a-d97ccf6794bf_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7339-b97a-d97ccf6794bf" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7339-b97a-d97ccf6794bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7c7d-aec1-ecae8195c482" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7339-b97a-d97ccf6794bf" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7c7d-aec1-ecae8195c482" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7e63-a2a8-0954994efe19" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-7c7d-aec1-ecae8195c482" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7e63-a2a8-0954994efe19" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_019e64ef-17ea-73dd-8ff4-9d2a71b89b99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-7418-a39b-05b77229c059" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_019e64ef-17ea-73dd-8ff4-9d2a71b89b99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_019e64ef-17ea-7dce-83dd-6c8d6d9d1179" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e64ef-17ea-7418-a39b-05b77229c059" xlink:to="loc_us-gaap_LongTermDebtFairValue_019e64ef-17ea-7dce-83dd-6c8d6d9d1179" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersACCGeneralRetailRateCasesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersACCGeneralRetailRateCasesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersACCGeneralRetailRateCasesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7767-b0eb-c177b86ff1f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7767-b0eb-c177b86ff1f1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7927-a9ae-84ed8d6bbe50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7767-b0eb-c177b86ff1f1" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7927-a9ae-84ed8d6bbe50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7927-a9ae-84ed8d6bbe50_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7927-a9ae-84ed8d6bbe50" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7927-a9ae-84ed8d6bbe50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-74bb-992d-b39749ff6eeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7927-a9ae-84ed8d6bbe50" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-74bb-992d-b39749ff6eeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7884-8b9a-439de6eac1cb" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-74bb-992d-b39749ff6eeb" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7884-8b9a-439de6eac1cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7ab3-8257-7bb502ef0ecf" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7767-b0eb-c177b86ff1f1" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7ab3-8257-7bb502ef0ecf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7ab3-8257-7bb502ef0ecf_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7ab3-8257-7bb502ef0ecf" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7ab3-8257-7bb502ef0ecf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-766a-bd28-055fb6367396" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7ab3-8257-7bb502ef0ecf" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-766a-bd28-055fb6367396" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-705a-97de-7175fcbf1214" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-766a-bd28-055fb6367396" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-705a-97de-7175fcbf1214" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7d5e-8861-8bb91b881e84" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-766a-bd28-055fb6367396" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7d5e-8861-8bb91b881e84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7682-ba38-f2e637167bc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7767-b0eb-c177b86ff1f1" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7682-ba38-f2e637167bc9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7682-ba38-f2e637167bc9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7682-ba38-f2e637167bc9" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7682-ba38-f2e637167bc9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-74f1-bb7a-1a6b9e2bddb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7682-ba38-f2e637167bc9" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-74f1-bb7a-1a6b9e2bddb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateCaseFilingWithArizonaCorporationCommissionMember_019e64ef-17ea-7961-b3fe-64146793c5cc" xlink:href="pnw-20260630.xsd#pnw_RateCaseFilingWithArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-74f1-bb7a-1a6b9e2bddb5" xlink:to="loc_pnw_RateCaseFilingWithArizonaCorporationCommissionMember_019e64ef-17ea-7961-b3fe-64146793c5cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e64ef-17ea-7efb-aaf3-60b8bbb796aa" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7767-b0eb-c177b86ff1f1" xlink:to="loc_srt_RangeAxis_019e64ef-17ea-7efb-aaf3-60b8bbb796aa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e64ef-17ea-7efb-aaf3-60b8bbb796aa_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e64ef-17ea-7efb-aaf3-60b8bbb796aa" xlink:to="loc_srt_RangeMember_019e64ef-17ea-7efb-aaf3-60b8bbb796aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e64ef-17ea-738a-8e4e-969351ec28e8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e64ef-17ea-7efb-aaf3-60b8bbb796aa" xlink:to="loc_srt_RangeMember_019e64ef-17ea-738a-8e4e-969351ec28e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e64ef-17ea-78e6-8cfe-a46484b08eb6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e64ef-17ea-738a-8e4e-969351ec28e8" xlink:to="loc_srt_MinimumMember_019e64ef-17ea-78e6-8cfe-a46484b08eb6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e64ef-17ea-72f2-8505-e7ef66ef21d9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e64ef-17ea-738a-8e4e-969351ec28e8" xlink:to="loc_srt_MaximumMember_019e64ef-17ea-72f2-8505-e7ef66ef21d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019e64ef-17ea-7474-888c-eeb14578b2a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019e64ef-17ea-7474-888c-eeb14578b2a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage_019e64ef-17ea-7bbe-a644-a586afec0e35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage_019e64ef-17ea-7bbe-a644-a586afec0e35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryImpactTotalRevenueDeficiency_019e64ef-17ea-7051-b295-2162c4c597b9" xlink:href="pnw-20260630.xsd#pnw_RegulatoryImpactTotalRevenueDeficiency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_RegulatoryImpactTotalRevenueDeficiency_019e64ef-17ea-7051-b295-2162c4c597b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesTestPeriod_019e64ef-17ea-7f04-b88e-e33b06826361" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesTestPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesTestPeriod_019e64ef-17ea-7f04-b88e-e33b06826361" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMatterCostBaseRate_019e64ef-17ea-778e-b718-8043a560bf7e" xlink:href="pnw-20260630.xsd#pnw_RateMatterCostBaseRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_RateMatterCostBaseRate_019e64ef-17ea-778e-b718-8043a560bf7e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryMattersBaseFuelAndPurchasedPowerCostsRate_019e64ef-17ea-75d7-8a7b-8086c0bbb5d9" xlink:href="pnw-20260630.xsd#pnw_RegulatoryMattersBaseFuelAndPurchasedPowerCostsRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_RegulatoryMattersBaseFuelAndPurchasedPowerCostsRate_019e64ef-17ea-75d7-8a7b-8086c0bbb5d9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage_019e64ef-17ea-7e9e-89b1-6611f5be9f39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage_019e64ef-17ea-7e9e-89b1-6611f5be9f39" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesIncrementOfFairValueRatePercentage_019e64ef-17ea-7c54-9bd2-5e8f8c70bdae" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesIncrementOfFairValueRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesIncrementOfFairValueRatePercentage_019e64ef-17ea-7c54-9bd2-5e8f8c70bdae" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedPeriodOfPostTestYearPlant_019e64ef-17ea-74be-9069-a1371c46e265" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedPeriodOfPostTestYearPlant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesRequestedPeriodOfPostTestYearPlant_019e64ef-17ea-74be-9069-a1371c46e265" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedNetRevenueRequirementIncreaseDecreaseAmount_019e64ef-17ea-798b-961d-937ed2d9b31e" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedNetRevenueRequirementIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesRequestedNetRevenueRequirementIncreaseDecreaseAmount_019e64ef-17ea-798b-961d-937ed2d9b31e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedIncreaseDecreaseInDeadband_019e64ef-17ea-7d31-8a78-07b27015210a" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedIncreaseDecreaseInDeadband"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesRequestedIncreaseDecreaseInDeadband_019e64ef-17ea-7d31-8a78-07b27015210a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedProjectedPlantDuration_019e64ef-17ea-7efe-b86c-b63514949051" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedProjectedPlantDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesRequestedProjectedPlantDuration_019e64ef-17ea-7efe-b86c-b63514949051" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedReviewAndChallengePeriod_019e64ef-17ea-7189-a2b5-16822846aed1" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedReviewAndChallengePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesRequestedReviewAndChallengePeriod_019e64ef-17ea-7189-a2b5-16822846aed1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019e64ef-17ea-7a23-8712-3b7f5eb21e78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019e64ef-17ea-7a23-8712-3b7f5eb21e78" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage_019e64ef-17ea-7b47-b65a-d197425d3172" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage_019e64ef-17ea-7b47-b65a-d197425d3172" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesEffectiveFairValueRatePercentage_019e64ef-17ea-7382-bf06-4531179a7601" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesEffectiveFairValueRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-709a-b646-16d9d3fcda92" xlink:to="loc_pnw_PublicUtilitiesEffectiveFairValueRatePercentage_019e64ef-17ea-7382-bf06-4531179a7601" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersScheduleOfCapitalStructureAndCostOfCapitalDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersScheduleOfCapitalStructureAndCostOfCapitalDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersScheduleOfCapitalStructureAndCostOfCapitalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7152-98f1-11dec45a4532" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7bdd-ad72-a49e2b7560d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7152-98f1-11dec45a4532" xlink:to="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7bdd-ad72-a49e2b7560d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7cc9-97b7-571beba5642d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7bdd-ad72-a49e2b7560d0" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7cc9-97b7-571beba5642d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7cc9-97b7-571beba5642d_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7cc9-97b7-571beba5642d" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7cc9-97b7-571beba5642d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7af1-8648-098191d94084" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7cc9-97b7-571beba5642d" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7af1-8648-098191d94084" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-78b2-8caf-f40eae30dd2b" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-7af1-8648-098191d94084" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-78b2-8caf-f40eae30dd2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-71f5-8430-deb197ccdaf8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7bdd-ad72-a49e2b7560d0" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-71f5-8430-deb197ccdaf8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-71f5-8430-deb197ccdaf8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-71f5-8430-deb197ccdaf8" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-71f5-8430-deb197ccdaf8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7860-8ff4-dbb0b04c5306" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-71f5-8430-deb197ccdaf8" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7860-8ff4-dbb0b04c5306" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateCaseFilingWithArizonaCorporationCommissionMember_019e64ef-17ea-721b-afaa-3af4cfcb6ace" xlink:href="pnw-20260630.xsd#pnw_RateCaseFilingWithArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7860-8ff4-dbb0b04c5306" xlink:to="loc_pnw_RateCaseFilingWithArizonaCorporationCommissionMember_019e64ef-17ea-721b-afaa-3af4cfcb6ace" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-735a-8d8c-159e4f81025c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-7bdd-ad72-a49e2b7560d0" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-735a-8d8c-159e4f81025c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-735a-8d8c-159e4f81025c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-735a-8d8c-159e4f81025c" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-735a-8d8c-159e4f81025c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7bcc-b1c0-d6b7b71de11f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-735a-8d8c-159e4f81025c" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7bcc-b1c0-d6b7b71de11f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7a56-9d3c-699fab3e6cab" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7bcc-b1c0-d6b7b71de11f" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7a56-9d3c-699fab3e6cab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CapitalStructureAbstract_019e64ef-17ea-7bd0-a6fd-95e0573008c5" xlink:href="pnw-20260630.xsd#pnw_CapitalStructureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7152-98f1-11dec45a4532" xlink:to="loc_pnw_CapitalStructureAbstract_019e64ef-17ea-7bd0-a6fd-95e0573008c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedDebtCapitalStructurePercentage_019e64ef-17ea-7484-ae1b-46e2da5c78f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRequestedDebtCapitalStructurePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_CapitalStructureAbstract_019e64ef-17ea-7bd0-a6fd-95e0573008c5" xlink:to="loc_us-gaap_PublicUtilitiesRequestedDebtCapitalStructurePercentage_019e64ef-17ea-7484-ae1b-46e2da5c78f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedEquityCapitalStructurePercentage_019e64ef-17ea-792b-9e71-586dcbe4a4b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRequestedEquityCapitalStructurePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_CapitalStructureAbstract_019e64ef-17ea-7bd0-a6fd-95e0573008c5" xlink:to="loc_us-gaap_PublicUtilitiesRequestedEquityCapitalStructurePercentage_019e64ef-17ea-792b-9e71-586dcbe4a4b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CostOfCapitalAbstract_019e64ef-17ea-7faf-8912-2f393493bf9f" xlink:href="pnw-20260630.xsd#pnw_CostOfCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7152-98f1-11dec45a4532" xlink:to="loc_pnw_CostOfCapitalAbstract_019e64ef-17ea-7faf-8912-2f393493bf9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedLongTermDebtCostOfCapitalPercentage_019e64ef-17ea-7a18-aacc-8e2c194088da" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedLongTermDebtCostOfCapitalPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_CostOfCapitalAbstract_019e64ef-17ea-7faf-8912-2f393493bf9f" xlink:to="loc_pnw_PublicUtilitiesRequestedLongTermDebtCostOfCapitalPercentage_019e64ef-17ea-7a18-aacc-8e2c194088da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedEquityCostOfCapitalPercentage_019e64ef-17ea-7ae5-99d5-6870773cfff9" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedEquityCostOfCapitalPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_CostOfCapitalAbstract_019e64ef-17ea-7faf-8912-2f393493bf9f" xlink:to="loc_pnw_PublicUtilitiesRequestedEquityCostOfCapitalPercentage_019e64ef-17ea-7ae5-99d5-6870773cfff9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRequestedWeightedAverageCostOfCapitalPercentage_019e64ef-17ea-7d20-a19f-1dca1f030fd9" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRequestedWeightedAverageCostOfCapitalPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_CostOfCapitalAbstract_019e64ef-17ea-7faf-8912-2f393493bf9f" xlink:to="loc_pnw_PublicUtilitiesRequestedWeightedAverageCostOfCapitalPercentage_019e64ef-17ea-7d20-a19f-1dca1f030fd9" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersCostRecoveryMechanismsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersCostRecoveryMechanismsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersCostRecoveryMechanismsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-769e-be5c-f292649054ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-769e-be5c-f292649054ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-769e-be5c-f292649054ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-769e-be5c-f292649054ea" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-769e-be5c-f292649054ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-769e-be5c-f292649054ea" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaRenewableEnergyStandardAndTariffMember_019e64ef-17ea-78da-b72a-373cddd32c0d" xlink:href="pnw-20260630.xsd#pnw_ArizonaRenewableEnergyStandardAndTariffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_ArizonaRenewableEnergyStandardAndTariffMember_019e64ef-17ea-78da-b72a-373cddd32c0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaRenewableEnergyStandardandTariff2018Member_019e64ef-17ea-7ac7-a5ba-cdd63a4e21bf" xlink:href="pnw-20260630.xsd#pnw_ArizonaRenewableEnergyStandardandTariff2018Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_ArizonaRenewableEnergyStandardandTariff2018Member_019e64ef-17ea-7ac7-a5ba-cdd63a4e21bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DemandSideManagementAdjustorCharge2024Member_019e64ef-17ea-7f9a-9e2a-97f1b5b53819" xlink:href="pnw-20260630.xsd#pnw_DemandSideManagementAdjustorCharge2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_DemandSideManagementAdjustorCharge2024Member_019e64ef-17ea-7f9a-9e2a-97f1b5b53819" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RenewableEnergyAdjustmentChargeMember_019e64ef-17ea-75a4-8bcc-f6f5b4aa5a8c" xlink:href="pnw-20260630.xsd#pnw_RenewableEnergyAdjustmentChargeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_RenewableEnergyAdjustmentChargeMember_019e64ef-17ea-75a4-8bcc-f6f5b4aa5a8c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DemandSideManagementAdjustorCharge2023Member_019e64ef-17ea-72c0-b474-a184bc2cebee" xlink:href="pnw-20260630.xsd#pnw_DemandSideManagementAdjustorCharge2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_DemandSideManagementAdjustorCharge2023Member_019e64ef-17ea-72c0-b474-a184bc2cebee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PowerSupplyAdjustorMember_019e64ef-17ea-7991-91d1-f545799495b5" xlink:href="pnw-20260630.xsd#pnw_PowerSupplyAdjustorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_PowerSupplyAdjustorMember_019e64ef-17ea-7991-91d1-f545799495b5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OpenAccessTransmissionTariffMember_019e64ef-17ea-7e0f-8b04-103d23270072" xlink:href="pnw-20260630.xsd#pnw_OpenAccessTransmissionTariffMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_OpenAccessTransmissionTariffMember_019e64ef-17ea-7e0f-8b04-103d23270072" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LostFixedCostRecoveryMechanismsMember_019e64ef-17ea-7e9a-b1cb-ede1226ce19f" xlink:href="pnw-20260630.xsd#pnw_LostFixedCostRecoveryMechanismsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_LostFixedCostRecoveryMechanismsMember_019e64ef-17ea-7e9a-b1cb-ede1226ce19f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CourtResolutionSurchargeMember_019e64ef-17ea-7c1d-ae55-5ef50dc05ae4" xlink:href="pnw-20260630.xsd#pnw_CourtResolutionSurchargeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_CourtResolutionSurchargeMember_019e64ef-17ea-7c1d-ae55-5ef50dc05ae4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NetMeteringMember_019e64ef-17ea-7b25-ad8c-3bf1a231470d" xlink:href="pnw-20260630.xsd#pnw_NetMeteringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_NetMeteringMember_019e64ef-17ea-7b25-ad8c-3bf1a231470d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_A2027RESImplementationPlanMember_019f65a1-4238-7bfb-9ceb-1a09f857db6b" xlink:href="pnw-20260630.xsd#pnw_A2027RESImplementationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7e0e-a955-0f55597cfe98" xlink:to="loc_pnw_A2027RESImplementationPlanMember_019f65a1-4238-7bfb-9ceb-1a09f857db6b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7151-92b3-79bce03f1f6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7151-92b3-79bce03f1f6b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7151-92b3-79bce03f1f6b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7151-92b3-79bce03f1f6b" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7151-92b3-79bce03f1f6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7d7f-b66f-dc308741a2ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7151-92b3-79bce03f1f6b" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7d7f-b66f-dc308741a2ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7ba9-adf1-56f068c96d7f" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7d7f-b66f-dc308741a2ef" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7ba9-adf1-56f068c96d7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember_019e64ef-17ea-7ac4-99c3-9d59b8e2f836" xlink:href="pnw-20260630.xsd#pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7d7f-b66f-dc308741a2ef" xlink:to="loc_pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember_019e64ef-17ea-7ac4-99c3-9d59b8e2f836" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7d18-996d-39028f225386" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7d18-996d-39028f225386" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7d18-996d-39028f225386_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7d18-996d-39028f225386" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7d18-996d-39028f225386_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7e36-a697-ad9b9d8229a9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7d18-996d-39028f225386" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7e36-a697-ad9b9d8229a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-72f9-8d3a-671946e95bfb" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-7e36-a697-ad9b9d8229a9" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-72f9-8d3a-671946e95bfb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7784-89eb-d90588c78f50" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-7e36-a697-ad9b9d8229a9" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7784-89eb-d90588c78f50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7233-86d9-abc86dff5bc1" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7233-86d9-abc86dff5bc1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7233-86d9-abc86dff5bc1_default" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7233-86d9-abc86dff5bc1" xlink:to="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7233-86d9-abc86dff5bc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-707b-a634-e12581ea433d" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7233-86d9-abc86dff5bc1" xlink:to="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-707b-a634-e12581ea433d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CostRecoveryMechanismsMember_019e64ef-17ea-7d55-952e-424399f77abb" xlink:href="pnw-20260630.xsd#pnw_CostRecoveryMechanismsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-707b-a634-e12581ea433d" xlink:to="loc_pnw_CostRecoveryMechanismsMember_019e64ef-17ea-7d55-952e-424399f77abb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-17ea-76b1-a58b-f917b04f77c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-17ea-76b1-a58b-f917b04f77c7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e64ef-17ea-76b1-a58b-f917b04f77c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-17ea-76b1-a58b-f917b04f77c7" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e64ef-17ea-76b1-a58b-f917b04f77c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e64ef-17ea-7480-a85f-74b446eeb70c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-17ea-76b1-a58b-f917b04f77c7" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e64ef-17ea-7480-a85f-74b446eeb70c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DamageFromFireExplosionOrOtherHazardMember_019e64ef-17ea-72d3-be22-4be0080ff2c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DamageFromFireExplosionOrOtherHazardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e64ef-17ea-7480-a85f-74b446eeb70c" xlink:to="loc_us-gaap_DamageFromFireExplosionOrOtherHazardMember_019e64ef-17ea-72d3-be22-4be0080ff2c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019eed2f-0b90-72c2-985b-c9f5777ebed6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_srt_StatementScenarioAxis_019eed2f-0b90-72c2-985b-c9f5777ebed6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019eed2f-0b90-72c2-985b-c9f5777ebed6_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019eed2f-0b90-72c2-985b-c9f5777ebed6" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019eed2f-0b90-72c2-985b-c9f5777ebed6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019eed2f-0b91-7ee2-85ca-9792576362c2" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019eed2f-0b90-72c2-985b-c9f5777ebed6" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019eed2f-0b91-7ee2-85ca-9792576362c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019eed2f-38e1-70c0-9222-08658382d6ab" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_019eed2f-0b91-7ee2-85ca-9792576362c2" xlink:to="loc_srt_ScenarioForecastMember_019eed2f-38e1-70c0-9222-08658382d6ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f65a1-8128-796b-af13-773c7a370757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-73af-ae7f-35825e398015" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f65a1-8128-796b-af13-773c7a370757" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f65a1-8128-796b-af13-773c7a370757_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f65a1-8128-796b-af13-773c7a370757" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f65a1-8128-796b-af13-773c7a370757_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f65a1-8128-7571-a298-f067b9f9b879" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f65a1-8128-796b-af13-773c7a370757" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f65a1-8128-7571-a298-f067b9f9b879" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f65a1-9882-7383-92c6-628b9225e0a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019f65a1-8128-7571-a298-f067b9f9b879" xlink:to="loc_us-gaap_SubsequentEventMember_019f65a1-9882-7383-92c6-628b9225e0a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMatterPlanTerm_019e64ef-17ea-7334-b669-5a89f9040dd4" xlink:href="pnw-20260630.xsd#pnw_RateMatterPlanTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMatterPlanTerm_019e64ef-17ea-7334-b669-5a89f9040dd4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMatterProposedBudget_019e64ef-17ea-78c7-ad4e-82cce15e1cc8" xlink:href="pnw-20260630.xsd#pnw_RateMatterProposedBudget"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMatterProposedBudget_019e64ef-17ea-78c7-ad4e-82cce15e1cc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesApprovedRateAmountOfCustomerRefunds_019e64ef-17ea-776d-b76f-8f2bfdc67f60" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesApprovedRateAmountOfCustomerRefunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_PublicUtilitiesApprovedRateAmountOfCustomerRefunds_019e64ef-17ea-776d-b76f-8f2bfdc67f60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMatterUpdatedBudget_019e64ef-17ea-7810-8981-3b08cb4140c2" xlink:href="pnw-20260630.xsd#pnw_RateMatterUpdatedBudget"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMatterUpdatedBudget_019e64ef-17ea-7810-8981-3b08cb4140c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MaximumIncreaseDecreaseinPSARate1_019e64ef-17ea-7294-99ea-fe3a1451799d" xlink:href="pnw-20260630.xsd#pnw_MaximumIncreaseDecreaseinPSARate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_MaximumIncreaseDecreaseinPSARate1_019e64ef-17ea-7294-99ea-fe3a1451799d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PSARateInPriorYears1_019e64ef-17ea-78bc-9955-03efa097845b" xlink:href="pnw-20260630.xsd#pnw_PSARateInPriorYears1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_PSARateInPriorYears1_019e64ef-17ea-78bc-9955-03efa097845b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PSARate1_019e64ef-17ea-74d8-a3a7-f64c2dbc3076" xlink:href="pnw-20260630.xsd#pnw_PSARate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_PSARate1_019e64ef-17ea-74d8-a3a7-f64c2dbc3076" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryClauseDeferredFuelAndPurchasedPowerCostsBalancingAccountReportingThresholdAmount_019e64ef-17ea-7bb1-9ebc-85c4722cb1d5" xlink:href="pnw-20260630.xsd#pnw_RegulatoryClauseDeferredFuelAndPurchasedPowerCostsBalancingAccountReportingThresholdAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RegulatoryClauseDeferredFuelAndPurchasedPowerCostsBalancingAccountReportingThresholdAmount_019e64ef-17ea-7bb1-9ebc-85c4722cb1d5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ApprovedPSARate1_019e64ef-17ea-7b01-9525-79d8873a662e" xlink:href="pnw-20260630.xsd#pnw_ApprovedPSARate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_ApprovedPSARate1_019e64ef-17ea-7b01-9525-79d8873a662e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ForwardComponentOfPSARate1_019e64ef-17ea-7855-8651-dbce9e978a54" xlink:href="pnw-20260630.xsd#pnw_ForwardComponentOfPSARate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_ForwardComponentOfPSARate1_019e64ef-17ea-7855-8651-dbce9e978a54" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_HistoricalComponentOfPSARate1_019e64ef-17ea-7d1d-a665-7e9c8d4e79fb" xlink:href="pnw-20260630.xsd#pnw_HistoricalComponentOfPSARate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_HistoricalComponentOfPSARate1_019e64ef-17ea-7d1d-a665-7e9c8d4e79fb" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TransitionComponentOfPSARate1_019e64ef-17ea-7cf2-b84c-464ede0559f6" xlink:href="pnw-20260630.xsd#pnw_TransitionComponentOfPSARate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_TransitionComponentOfPSARate1_019e64ef-17ea-7cf2-b84c-464ede0559f6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersIncreaseDecreaseInCostRecovery_019e64ef-17ea-7e44-9825-6609490b7dd5" xlink:href="pnw-20260630.xsd#pnw_RateMattersIncreaseDecreaseInCostRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersIncreaseDecreaseInCostRecovery_019e64ef-17ea-7e44-9825-6609490b7dd5" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersIncreaseDecreaseInCostRecoveryWholesaleCustomerRates_019e64ef-17ea-72df-bdc4-7a9704b579e4" xlink:href="pnw-20260630.xsd#pnw_RateMattersIncreaseDecreaseInCostRecoveryWholesaleCustomerRates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersIncreaseDecreaseInCostRecoveryWholesaleCustomerRates_019e64ef-17ea-72df-bdc4-7a9704b579e4" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersIncreaseDecreaseInCostRecoveryRetailCustomerRates_019e64ef-17ea-7770-b53c-fe075b0cada0" xlink:href="pnw-20260630.xsd#pnw_RateMattersIncreaseDecreaseInCostRecoveryRetailCustomerRates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersIncreaseDecreaseInCostRecoveryRetailCustomerRates_019e64ef-17ea-7770-b53c-fe075b0cada0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersIncreaseDecreaseInRetailRevenueRequirements_019e64ef-17ea-7649-be95-56ecf78e0658" xlink:href="pnw-20260630.xsd#pnw_RateMattersIncreaseDecreaseInRetailRevenueRequirements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersIncreaseDecreaseInRetailRevenueRequirements_019e64ef-17ea-7649-be95-56ecf78e0658" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersIncreaseInResidentialAndCommercialRatesPower_019e64ef-17ea-71de-b526-56628bc854d3" xlink:href="pnw-20260630.xsd#pnw_RateMattersIncreaseInResidentialAndCommercialRatesPower"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersIncreaseInResidentialAndCommercialRatesPower_019e64ef-17ea-71de-b526-56628bc854d3" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersDecreaseInCommercialRatesPower_019e64ef-17ea-7247-afca-121d812c73a0" xlink:href="pnw-20260630.xsd#pnw_RateMattersDecreaseInCommercialRatesPower"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersDecreaseInCommercialRatesPower_019e64ef-17ea-7247-afca-121d812c73a0" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMatterCapPercentageOfRetailRevenue_019e64ef-17ea-7cf3-bf49-0d236564a02a" xlink:href="pnw-20260630.xsd#pnw_RateMatterCapPercentageOfRetailRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMatterCapPercentageOfRetailRevenue_019e64ef-17ea-7cf3-bf49-0d236564a02a" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AmountofAdjustmentRepresentingProratedSalesLossesPendingApproval_019e64ef-17ea-7a7e-94b0-10b4ac051017" xlink:href="pnw-20260630.xsd#pnw_AmountofAdjustmentRepresentingProratedSalesLossesPendingApproval"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_AmountofAdjustmentRepresentingProratedSalesLossesPendingApproval_019e64ef-17ea-7a7e-94b0-10b4ac051017" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncreaseDecreaseInAmountOfAdjustmentRepresentingAnnualRecovery_019e64ef-17ea-70d7-93bc-d80e5df95ec2" xlink:href="pnw-20260630.xsd#pnw_IncreaseDecreaseInAmountOfAdjustmentRepresentingAnnualRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_IncreaseDecreaseInAmountOfAdjustmentRepresentingAnnualRecovery_019e64ef-17ea-70d7-93bc-d80e5df95ec2" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersCourtResolutionSurchargeCapRate1_019e64ef-17ea-7fde-880a-8eeec8fc6df3" xlink:href="pnw-20260630.xsd#pnw_RateMattersCourtResolutionSurchargeCapRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersCourtResolutionSurchargeCapRate1_019e64ef-17ea-7fde-880a-8eeec8fc6df3" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryMattersRequestedRateIncreaseLostRevenueRecoveryAndOngoingCosts_019e64ef-17ea-7b49-92cf-784994c905be" xlink:href="pnw-20260630.xsd#pnw_RegulatoryMattersRequestedRateIncreaseLostRevenueRecoveryAndOngoingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RegulatoryMattersRequestedRateIncreaseLostRevenueRecoveryAndOngoingCosts_019e64ef-17ea-7b49-92cf-784994c905be" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryMattersRequestedRateIncreaseLostRevenueRecoveryAndOngoingCostsCollected_019e64ef-17ea-7612-b747-4b29facb5bdb" xlink:href="pnw-20260630.xsd#pnw_RegulatoryMattersRequestedRateIncreaseLostRevenueRecoveryAndOngoingCostsCollected"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RegulatoryMattersRequestedRateIncreaseLostRevenueRecoveryAndOngoingCostsCollected_019e64ef-17ea-7612-b747-4b29facb5bdb" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersCostOfServiceResourceComparisonProxyMethodMaximumAnnualPercentageDecrease_019e64ef-17ea-79f6-abbb-fae55971a617" xlink:href="pnw-20260630.xsd#pnw_RateMattersCostOfServiceResourceComparisonProxyMethodMaximumAnnualPercentageDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersCostOfServiceResourceComparisonProxyMethodMaximumAnnualPercentageDecrease_019e64ef-17ea-79f6-abbb-fae55971a617" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMatterRequestThirdYearEnergyPriceForExportedEnergy1_019e64ef-17ea-7cea-b062-529313f3e9f4" xlink:href="pnw-20260630.xsd#pnw_RateMatterRequestThirdYearEnergyPriceForExportedEnergy1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMatterRequestThirdYearEnergyPriceForExportedEnergy1_019e64ef-17ea-7cea-b062-529313f3e9f4" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateMattersResourceComparisonProxyMethodRateLockPeriod_019e64ef-17ea-7311-95fe-8294bbf26d24" xlink:href="pnw-20260630.xsd#pnw_RateMattersResourceComparisonProxyMethodRateLockPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_RateMattersResourceComparisonProxyMethodRateLockPeriod_019e64ef-17ea-7311-95fe-8294bbf26d24" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CustomerSupportFundPastDueBalanceThreshold_019e64ef-17ea-7cd2-a486-9828f45f52aa" xlink:href="pnw-20260630.xsd#pnw_CustomerSupportFundPastDueBalanceThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-70fc-8806-63409d0afd07" xlink:to="loc_pnw_CustomerSupportFundPastDueBalanceThreshold_019e64ef-17ea-7cd2-a486-9828f45f52aa" xlink:type="arc" order="27"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersScheduleofChangesinTheDeferredFuelandPurchasedPowerRegulatoryAssetDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersScheduleofChangesinTheDeferredFuelandPurchasedPowerRegulatoryAssetDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersScheduleofChangesinTheDeferredFuelandPurchasedPowerRegulatoryAssetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7d96-840c-4d2c11cad54a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-78fd-b9b2-a7a320c53591" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7d96-840c-4d2c11cad54a" xlink:to="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-78fd-b9b2-a7a320c53591" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7f76-8fe6-382a0cc600e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-78fd-b9b2-a7a320c53591" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7f76-8fe6-382a0cc600e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7f76-8fe6-382a0cc600e0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7f76-8fe6-382a0cc600e0" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7f76-8fe6-382a0cc600e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-746a-be61-e9087b39a02c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7f76-8fe6-382a0cc600e0" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-746a-be61-e9087b39a02c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PowerSupplyAdjustorMember_019e64ef-17ea-7560-bff5-676198a38e07" xlink:href="pnw-20260630.xsd#pnw_PowerSupplyAdjustorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-746a-be61-e9087b39a02c" xlink:to="loc_pnw_PowerSupplyAdjustorMember_019e64ef-17ea-7560-bff5-676198a38e07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7a50-b48a-391a3df0b97b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-78fd-b9b2-a7a320c53591" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7a50-b48a-391a3df0b97b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7a50-b48a-391a3df0b97b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7a50-b48a-391a3df0b97b" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7a50-b48a-391a3df0b97b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7894-b0b0-28d487658708" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7a50-b48a-391a3df0b97b" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7894-b0b0-28d487658708" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7129-9a4e-fe7d37cdcdc2" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7894-b0b0-28d487658708" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-7129-9a4e-fe7d37cdcdc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7424-a719-792027f1c5e5" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_019e64ef-17ea-78fd-b9b2-a7a320c53591" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7424-a719-792027f1c5e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7424-a719-792027f1c5e5_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7424-a719-792027f1c5e5" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7424-a719-792027f1c5e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-700f-bd6e-79a4a9550719" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7424-a719-792027f1c5e5" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-700f-bd6e-79a4a9550719" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7d96-a57c-7d71e57300bb" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-700f-bd6e-79a4a9550719" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-7d96-a57c-7d71e57300bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward_019e64ef-17ea-7588-9a45-d84d62e3b171" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_019e64ef-17ea-7d96-840c-4d2c11cad54a" xlink:to="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward_019e64ef-17ea-7588-9a45-d84d62e3b171" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityCurrent_019e64ef-17ea-730d-b86b-200f06d6c0bd" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward_019e64ef-17ea-7588-9a45-d84d62e3b171" xlink:to="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityCurrent_019e64ef-17ea-730d-b86b-200f06d6c0bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue_019e64ef-17ea-7271-8758-1d5af3e85a3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward_019e64ef-17ea-7588-9a45-d84d62e3b171" xlink:to="loc_us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue_019e64ef-17ea-7271-8758-1d5af3e85a3a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization_019e64ef-17ea-71c0-b066-00d49fb2d4fe" xlink:href="pnw-20260630.xsd#pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward_019e64ef-17ea-7588-9a45-d84d62e3b171" xlink:to="loc_pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization_019e64ef-17ea-71c0-b066-00d49fb2d4fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityCurrent_019e64ef-17ea-7314-b556-e6e0b1143f61" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityCurrent"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersChollaandNavajoPlantDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersChollaandNavajoPlantDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersChollaandNavajoPlantDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019e64ef-17ea-7350-b4b2-c9b996e31f71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e64ef-17ea-7350-b4b2-c9b996e31f71" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7cc9-bd16-cfbf2ea361fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7cc9-bd16-cfbf2ea361fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7cc9-bd16-cfbf2ea361fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7cc9-bd16-cfbf2ea361fd" xlink:to="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7cc9-bd16-cfbf2ea361fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7cc9-bd16-cfbf2ea361fd" xlink:to="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ChollaUnits13Member_019e64ef-17ea-78ed-873d-d342f127f7c4" xlink:href="pnw-20260630.xsd#pnw_ChollaUnits13Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:to="loc_pnw_ChollaUnits13Member_019e64ef-17ea-78ed-873d-d342f127f7c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RetiredPowerPlantCostsMember_019e64ef-17ea-7772-8c54-d7244752ca18" xlink:href="pnw-20260630.xsd#pnw_RetiredPowerPlantCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:to="loc_pnw_RetiredPowerPlantCostsMember_019e64ef-17ea-7772-8c54-d7244752ca18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ChollaMember_019f65a7-4dc9-7e28-b5c5-793bfadf4455" xlink:href="pnw-20260630.xsd#pnw_ChollaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:to="loc_pnw_ChollaMember_019f65a7-4dc9-7e28-b5c5-793bfadf4455" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NavajoPlantMember_019e64ef-17ea-76f3-bb37-9f8eaee67410" xlink:href="pnw-20260630.xsd#pnw_NavajoPlantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:to="loc_pnw_NavajoPlantMember_019e64ef-17ea-76f3-bb37-9f8eaee67410" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NavajoPlantCoalReclamationRegulatoryAssetMember_019e64ef-17ea-76ec-b9e4-f8e597a7e3ba" xlink:href="pnw-20260630.xsd#pnw_NavajoPlantCoalReclamationRegulatoryAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-79c1-9831-6d607478c113" xlink:to="loc_pnw_NavajoPlantCoalReclamationRegulatoryAssetMember_019e64ef-17ea-76ec-b9e4-f8e597a7e3ba" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-17ea-7eba-8bab-abc3f2a747f0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_dei_LegalEntityAxis_019e64ef-17ea-7eba-8bab-abc3f2a747f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-7eba-8bab-abc3f2a747f0_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7eba-8bab-abc3f2a747f0" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-7eba-8bab-abc3f2a747f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-17ea-70e6-9a71-39b1b8a47caf" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-17ea-7eba-8bab-abc3f2a747f0" xlink:to="loc_dei_EntityDomain_019e64ef-17ea-70e6-9a71-39b1b8a47caf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-79d1-8eb1-e7a11f0aeebd" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-17ea-70e6-9a71-39b1b8a47caf" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-17ea-79d1-8eb1-e7a11f0aeebd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7f7b-808d-7fa59ec65530" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7f7b-808d-7fa59ec65530" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7f7b-808d-7fa59ec65530_default" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7f7b-808d-7fa59ec65530" xlink:to="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7f7b-808d-7fa59ec65530_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7be8-97bc-501944998191" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis_019e64ef-17ea-7f7b-808d-7fa59ec65530" xlink:to="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7be8-97bc-501944998191" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NavajoNationEconomicDevelopmentOrganizationMember_019e64ef-17ea-7c8f-9595-6bcc818f43bf" xlink:href="pnw-20260630.xsd#pnw_NavajoNationEconomicDevelopmentOrganizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_PublicUtilitiesRegulatoryRegulatoryMattersDomain_019e64ef-17ea-7be8-97bc-501944998191" xlink:to="loc_pnw_NavajoNationEconomicDevelopmentOrganizationMember_019e64ef-17ea-7c8f-9595-6bcc818f43bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilityProgramAxis_019e64ef-17ea-77f8-8cd8-c4ce2471b921" xlink:href="pnw-20260630.xsd#pnw_PublicUtilityProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_pnw_PublicUtilityProgramAxis_019e64ef-17ea-77f8-8cd8-c4ce2471b921" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilityProgramDomain_019e64ef-17ea-77f8-8cd8-c4ce2471b921_default" xlink:href="pnw-20260630.xsd#pnw_PublicUtilityProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnw_PublicUtilityProgramAxis_019e64ef-17ea-77f8-8cd8-c4ce2471b921" xlink:to="loc_pnw_PublicUtilityProgramDomain_019e64ef-17ea-77f8-8cd8-c4ce2471b921_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilityProgramDomain_019e64ef-17ea-7434-aefa-18708c160c79" xlink:href="pnw-20260630.xsd#pnw_PublicUtilityProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnw_PublicUtilityProgramAxis_019e64ef-17ea-77f8-8cd8-c4ce2471b921" xlink:to="loc_pnw_PublicUtilityProgramDomain_019e64ef-17ea-7434-aefa-18708c160c79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CoalCommunityTransitionPlanMember_019e64ef-17ea-7a55-a576-7f7b76bcd644" xlink:href="pnw-20260630.xsd#pnw_CoalCommunityTransitionPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_PublicUtilityProgramDomain_019e64ef-17ea-7434-aefa-18708c160c79" xlink:to="loc_pnw_CoalCommunityTransitionPlanMember_019e64ef-17ea-7a55-a576-7f7b76bcd644" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7890-8b63-c409ec3974e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7890-8b63-c409ec3974e8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7890-8b63-c409ec3974e8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7890-8b63-c409ec3974e8" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-7890-8b63-c409ec3974e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-75e0-bdce-25f2d7857866" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesRegulatoryProceedingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019e64ef-17ea-7890-8b63-c409ec3974e8" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-75e0-bdce-25f2d7857866" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RateCaseFilingWithArizonaCorporationCommissionMember_019e64ef-17ea-77f5-9b21-c6805018a092" xlink:href="pnw-20260630.xsd#pnw_RateCaseFilingWithArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019e64ef-17ea-75e0-bdce-25f2d7857866" xlink:to="loc_pnw_RateCaseFilingWithArizonaCorporationCommissionMember_019e64ef-17ea-77f5-9b21-c6805018a092" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7720-8c6e-3bb83c110468" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7720-8c6e-3bb83c110468" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7720-8c6e-3bb83c110468_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7720-8c6e-3bb83c110468" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7720-8c6e-3bb83c110468_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7a44-b338-db73e1a5fe1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7720-8c6e-3bb83c110468" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7a44-b338-db73e1a5fe1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-79e3-a8ea-9531a30b292b" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7a44-b338-db73e1a5fe1d" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-79e3-a8ea-9531a30b292b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f65a9-3aa3-73af-a172-a8e7140743ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e64ef-17ea-7e39-8e1e-bb6afd94545a" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f65a9-3aa3-73af-a172-a8e7140743ae" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f65a9-3aa3-73af-a172-a8e7140743ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f65a9-3aa3-73af-a172-a8e7140743ae" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f65a9-3aa3-73af-a172-a8e7140743ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f65a9-3aa3-7fa9-a167-018eb9cc8749" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f65a9-3aa3-73af-a172-a8e7140743ae" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f65a9-3aa3-7fa9-a167-018eb9cc8749" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f65a9-54f7-7f52-8d5b-9fdc62bbaea2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019f65a9-3aa3-7fa9-a167-018eb9cc8749" xlink:to="loc_us-gaap_SubsequentEventMember_019f65a9-54f7-7f52-8d5b-9fdc62bbaea2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryAssetNetBookValue_019e64ef-17ea-7bb9-9e71-2eb63d603b0a" xlink:href="pnw-20260630.xsd#pnw_RegulatoryAssetNetBookValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e64ef-17ea-7350-b4b2-c9b996e31f71" xlink:to="loc_pnw_RegulatoryAssetNetBookValue_019e64ef-17ea-7bb9-9e71-2eb63d603b0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PublicUtilitiesDisallowanceOfAnnualAmortizationPercentage_019e64ef-17ea-7bbc-9f38-9f99d25008fe" xlink:href="pnw-20260630.xsd#pnw_PublicUtilitiesDisallowanceOfAnnualAmortizationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e64ef-17ea-7350-b4b2-c9b996e31f71" xlink:to="loc_pnw_PublicUtilitiesDisallowanceOfAnnualAmortizationPercentage_019e64ef-17ea-7bbc-9f38-9f99d25008fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryAssetPlannedConversionNumberOfUnits_019f65a6-7247-7f76-905d-8edac1b0bf42" xlink:href="pnw-20260630.xsd#pnw_RegulatoryAssetPlannedConversionNumberOfUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e64ef-17ea-7350-b4b2-c9b996e31f71" xlink:to="loc_pnw_RegulatoryAssetPlannedConversionNumberOfUnits_019f65a6-7247-7f76-905d-8edac1b0bf42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryAssetPotentialIncreaseInGenerationCapacity_019f65a8-b990-7ed6-8c17-4680796dc413" xlink:href="pnw-20260630.xsd#pnw_RegulatoryAssetPotentialIncreaseInGenerationCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e64ef-17ea-7350-b4b2-c9b996e31f71" xlink:to="loc_pnw_RegulatoryAssetPotentialIncreaseInGenerationCapacity_019f65a8-b990-7ed6-8c17-4680796dc413" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersScheduleofRegulatoryAssetsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersScheduleofRegulatoryAssetsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersScheduleofRegulatoryAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetLineItems_019e64ef-17ea-7149-819e-2df07308f5b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019e64ef-17ea-7893-9586-69afb2622bb0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRegulatoryAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RegulatoryAssetLineItems_019e64ef-17ea-7149-819e-2df07308f5b5" xlink:to="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019e64ef-17ea-7893-9586-69afb2622bb0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7401-a79d-b708890aacb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019e64ef-17ea-7893-9586-69afb2622bb0" xlink:to="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7401-a79d-b708890aacb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7401-a79d-b708890aacb8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7401-a79d-b708890aacb8" xlink:to="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7401-a79d-b708890aacb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAssetAxis_019e64ef-17ea-7401-a79d-b708890aacb8" xlink:to="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PensionMember_019e64ef-17ea-71cc-8eda-a0351a372b2f" xlink:href="pnw-20260630.xsd#pnw_PensionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_PensionMember_019e64ef-17ea-71cc-8eda-a0351a372b2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncomeTaxesAFUDCEquityMember_019e64ef-17ea-75b0-b657-da8360275943" xlink:href="pnw-20260630.xsd#pnw_IncomeTaxesAFUDCEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_IncomeTaxesAFUDCEquityMember_019e64ef-17ea-75b0-b657-da8360275943" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PaloVerdeSaleLeasebackNCIAcquisitionMember_019e64ef-17ea-70a4-8a7e-6bb5ea208792" xlink:href="pnw-20260630.xsd#pnw_PaloVerdeSaleLeasebackNCIAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_PaloVerdeSaleLeasebackNCIAcquisitionMember_019e64ef-17ea-70a4-8a7e-6bb5ea208792" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OctotilloDeferralMember_019e64ef-17ea-7d90-ba04-f04f414f4de5" xlink:href="pnw-20260630.xsd#pnw_OctotilloDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_OctotilloDeferralMember_019e64ef-17ea-7d90-ba04-f04f414f4de5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LeaseIncentivesMember_019e64ef-17ea-76e1-9c88-5e12ffd12885" xlink:href="pnw-20260630.xsd#pnw_LeaseIncentivesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_LeaseIncentivesMember_019e64ef-17ea-76e1-9c88-5e12ffd12885" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerMTMCostsMember_019e64ef-17ea-798a-98dc-019a8a975a2c" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerMTMCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_DeferredFuelAndPurchasedPowerMTMCostsMember_019e64ef-17ea-798a-98dc-019a8a975a2c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SCRDeferralMember_019e64ef-17ea-7852-8e56-d27f89a3a932" xlink:href="pnw-20260630.xsd#pnw_SCRDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_SCRDeferralMember_019e64ef-17ea-7852-8e56-d27f89a3a932" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RetiredPowerPlantCostsMember_019e64ef-17ea-7ab0-b3ea-e5d24df7521d" xlink:href="pnw-20260630.xsd#pnw_RetiredPowerPlantCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_RetiredPowerPlantCostsMember_019e64ef-17ea-7ab0-b3ea-e5d24df7521d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncomeTaxesInvestmentTaxCreditBasisAdjustmentMember_019e64ef-17ea-74f4-b61d-b09401d5be01" xlink:href="pnw-20260630.xsd#pnw_IncomeTaxesInvestmentTaxCreditBasisAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_IncomeTaxesInvestmentTaxCreditBasisAdjustmentMember_019e64ef-17ea-74f4-b61d-b09401d5be01" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredCompensationMember_019e64ef-17ea-743d-80b9-d2441baa1ab7" xlink:href="pnw-20260630.xsd#pnw_DeferredCompensationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_DeferredCompensationMember_019e64ef-17ea-743d-80b9-d2441baa1ab7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_FERCTransmissionTrueUpMember_019e64ef-17ea-7ff5-afbd-b6acb46e2d39" xlink:href="pnw-20260630.xsd#pnw_FERCTransmissionTrueUpMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_FERCTransmissionTrueUpMember_019e64ef-17ea-7ff5-afbd-b6acb46e2d39" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredPropertyTaxesMember_019e64ef-17ea-7d31-bacb-d9a390fc214d" xlink:href="pnw-20260630.xsd#pnw_DeferredPropertyTaxesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_DeferredPropertyTaxesMember_019e64ef-17ea-7d31-bacb-d9a390fc214d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-17ea-7307-833e-bacf1416cc06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-17ea-7307-833e-bacf1416cc06" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MeadPhoenixtransmissionlineCIACMember_019e64ef-17ea-7f17-bbe6-eea62b52d19e" xlink:href="pnw-20260630.xsd#pnw_MeadPhoenixtransmissionlineCIACMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_MeadPhoenixtransmissionlineCIACMember_019e64ef-17ea-7f17-bbe6-eea62b52d19e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossOnReacquiredDebtMember_019e64ef-17ea-7b81-bc64-1407af0cd5f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossOnReacquiredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_us-gaap_LossOnReacquiredDebtMember_019e64ef-17ea-7b81-bc64-1407af0cd5f0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ActiveUnionMedicalTrustMember_019e64ef-17ea-76f3-8a34-30ff4577cf51" xlink:href="pnw-20260630.xsd#pnw_ActiveUnionMedicalTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_ActiveUnionMedicalTrustMember_019e64ef-17ea-76f3-8a34-30ff4577cf51" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TaxExpenseAdjustorMechanismMember_019e64ef-17ea-74e9-a8d2-8adb231f8590" xlink:href="pnw-20260630.xsd#pnw_TaxExpenseAdjustorMechanismMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_TaxExpenseAdjustorMechanismMember_019e64ef-17ea-74e9-a8d2-8adb231f8590" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PowerSupplyAdjustorInterestMember_019e64ef-17ea-72ee-a709-795409b9224e" xlink:href="pnw-20260630.xsd#pnw_PowerSupplyAdjustorInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_PowerSupplyAdjustorInterestMember_019e64ef-17ea-72ee-a709-795409b9224e" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NavajoCoalReclamationMember_019e64ef-17ea-729a-83f4-c14c1e5a0b09" xlink:href="pnw-20260630.xsd#pnw_NavajoCoalReclamationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_NavajoCoalReclamationMember_019e64ef-17ea-729a-83f4-c14c1e5a0b09" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelandPurchasedPowerMember_019e64ef-17ea-7c68-82df-790a681c0a67" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelandPurchasedPowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_DeferredFuelandPurchasedPowerMember_019e64ef-17ea-7c68-82df-790a681c0a67" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DemandSideManagementMember_019e64ef-17ea-728b-84b6-12f37ce03960" xlink:href="pnw-20260630.xsd#pnw_DemandSideManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_pnw_DemandSideManagementMember_019e64ef-17ea-728b-84b6-12f37ce03960" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRegulatoryAssetsLiabilitiesMember_019e64ef-17ea-7158-8e08-dc13389896ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherRegulatoryAssetsLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_019e64ef-17ea-7c58-abae-445b2827cd34" xlink:to="loc_us-gaap_OtherRegulatoryAssetsLiabilitiesMember_019e64ef-17ea-7158-8e08-dc13389896ad" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019e64ef-17ea-7ff3-b1ae-3b4ec537403a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetLineItems_019e64ef-17ea-7149-819e-2df07308f5b5" xlink:to="loc_us-gaap_RegulatoryAssets_019e64ef-17ea-7ff3-b1ae-3b4ec537403a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsCurrent_019e64ef-17ea-7c7c-bc7b-53ba702a4f26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetLineItems_019e64ef-17ea-7149-819e-2df07308f5b5" xlink:to="loc_us-gaap_RegulatoryAssetsCurrent_019e64ef-17ea-7c7c-bc7b-53ba702a4f26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsNoncurrent_019e64ef-17ea-7dc5-8945-c438d91c9050" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetLineItems_019e64ef-17ea-7149-819e-2df07308f5b5" xlink:to="loc_us-gaap_RegulatoryAssetsNoncurrent_019e64ef-17ea-7dc5-8945-c438d91c9050" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RegulatoryMattersScheduleofRegulatoryLiabilitiesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RegulatoryMattersScheduleofRegulatoryLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RegulatoryMattersScheduleofRegulatoryLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilitiesLineItems_019e64ef-17ea-7d5e-9e3c-84cf6832be23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_019e64ef-17ea-7336-8384-69c2f221493d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRegulatoryLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_019e64ef-17ea-7d5e-9e3c-84cf6832be23" xlink:to="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_019e64ef-17ea-7336-8384-69c2f221493d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7acb-afbd-efdca4974066" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_019e64ef-17ea-7336-8384-69c2f221493d" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7acb-afbd-efdca4974066" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7acb-afbd-efdca4974066_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7acb-afbd-efdca4974066" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7acb-afbd-efdca4974066_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7740-b5a7-a973616f01a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_019e64ef-17ea-7acb-afbd-efdca4974066" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7740-b5a7-a973616f01a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-71d9-9ab0-631c6ecfe5bb" xlink:href="pnw-20260630.xsd#pnw_ArizonaCorporationCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7740-b5a7-a973616f01a0" xlink:to="loc_pnw_ArizonaCorporationCommissionMember_019e64ef-17ea-71d9-9ab0-631c6ecfe5bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember_019e64ef-17ea-7b33-be7e-164b929adf05" xlink:href="pnw-20260630.xsd#pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019e64ef-17ea-7740-b5a7-a973616f01a0" xlink:to="loc_pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember_019e64ef-17ea-7b33-be7e-164b929adf05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityAxis_019e64ef-17ea-7640-8726-3e33ff71281d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_019e64ef-17ea-7336-8384-69c2f221493d" xlink:to="loc_us-gaap_RegulatoryLiabilityAxis_019e64ef-17ea-7640-8726-3e33ff71281d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7640-8726-3e33ff71281d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryLiabilityAxis_019e64ef-17ea-7640-8726-3e33ff71281d" xlink:to="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7640-8726-3e33ff71281d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryLiabilityAxis_019e64ef-17ea-7640-8726-3e33ff71281d" xlink:to="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TaxCutsandJobsActof2017ExcessDeferredIncomeTaxesMember_019e64ef-17ea-7573-b370-a3678cedbdda" xlink:href="pnw-20260630.xsd#pnw_TaxCutsandJobsActof2017ExcessDeferredIncomeTaxesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_TaxCutsandJobsActof2017ExcessDeferredIncomeTaxesMember_019e64ef-17ea-7573-b370-a3678cedbdda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationCostsMember_019e64ef-17ea-7c45-8e06-ef2ce480a281" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_us-gaap_AssetRetirementObligationCostsMember_019e64ef-17ea-7c45-8e06-ef2ce480a281" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PostretirementBenefitCostsMember_019e64ef-17ea-77fd-ba8c-002fecf6f5bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PostretirementBenefitCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_us-gaap_PostretirementBenefitCostsMember_019e64ef-17ea-77fd-ba8c-002fecf6f5bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_FourCornersCoalReclamationMember_019e64ef-17ea-7424-a94a-5c6e5c8b6372" xlink:href="pnw-20260630.xsd#pnw_FourCornersCoalReclamationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_FourCornersCoalReclamationMember_019e64ef-17ea-7424-a94a-5c6e5c8b6372" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxChargesMember_019e64ef-17ea-7960-a1c9-a1c003019b16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxChargesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_us-gaap_DeferredIncomeTaxChargesMember_019e64ef-17ea-7960-a1c9-a1c003019b16" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelandPurchasedPowerMember_019f6124-7edb-7ca7-937e-978e613d1691" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelandPurchasedPowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_DeferredFuelandPurchasedPowerMember_019f6124-7edb-7ca7-937e-978e613d1691" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncomeTaxesChangeInRatesMember_019e64ef-17ea-7359-8db0-503db54c7dd8" xlink:href="pnw-20260630.xsd#pnw_IncomeTaxesChangeInRatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_IncomeTaxesChangeInRatesMember_019e64ef-17ea-7359-8db0-503db54c7dd8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RenewableEnergyProgramMember_019e64ef-17ea-7259-b4ac-33efe27fc391" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RenewableEnergyProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_us-gaap_RenewableEnergyProgramMember_019e64ef-17ea-7259-b4ac-33efe27fc391" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SundanceMaintenanceMember_019e64ef-17ea-7b3a-b14a-71467afc963e" xlink:href="pnw-20260630.xsd#pnw_SundanceMaintenanceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_SundanceMaintenanceMember_019e64ef-17ea-7b3a-b14a-71467afc963e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SpentNuclearFuelMember_019e64ef-17ea-762e-bc59-3520a572b29e" xlink:href="pnw-20260630.xsd#pnw_SpentNuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_SpentNuclearFuelMember_019e64ef-17ea-762e-bc59-3520a572b29e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DemandSideManagementMember_019e64ef-17ea-7390-968a-481bb0cac904" xlink:href="pnw-20260630.xsd#pnw_DemandSideManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_DemandSideManagementMember_019e64ef-17ea-7390-968a-481bb0cac904" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TCABalancingAccountMember_019e64ef-17ea-7a08-87a0-54d499ca5846" xlink:href="pnw-20260630.xsd#pnw_TCABalancingAccountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_TCABalancingAccountMember_019e64ef-17ea-7a08-87a0-54d499ca5846" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_TaxExpenseAdjustorMechanismMember_019e64ef-17ea-7d81-9404-01fd0d331f7b" xlink:href="pnw-20260630.xsd#pnw_TaxExpenseAdjustorMechanismMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_TaxExpenseAdjustorMechanismMember_019e64ef-17ea-7d81-9404-01fd0d331f7b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DeferredFuelAndPurchasedPowerMTMCostsMember_019e64ef-17ea-7317-abfe-7b50fe9eb8e5" xlink:href="pnw-20260630.xsd#pnw_DeferredFuelAndPurchasedPowerMTMCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_DeferredFuelAndPurchasedPowerMTMCostsMember_019e64ef-17ea-7317-abfe-7b50fe9eb8e5" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OtherRegulatoryLiabilitiesMember_019e64ef-17ea-77e3-a59f-30e5cdca8066" xlink:href="pnw-20260630.xsd#pnw_OtherRegulatoryLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019e64ef-17ea-7c07-ae51-e652e1c0d5cd" xlink:to="loc_pnw_OtherRegulatoryLiabilitiesMember_019e64ef-17ea-77e3-a59f-30e5cdca8066" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilities_019e64ef-17ea-7ce1-a759-7405f4b276a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_019e64ef-17ea-7d5e-9e3c-84cf6832be23" xlink:to="loc_us-gaap_RegulatoryLiabilities_019e64ef-17ea-7ce1-a759-7405f4b276a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RegulatoryLiabilityIncludingDeferredChargesCurrent_019e64ef-17ea-78a3-af6d-adfc047a9942" xlink:href="pnw-20260630.xsd#pnw_RegulatoryLiabilityIncludingDeferredChargesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_019e64ef-17ea-7d5e-9e3c-84cf6832be23" xlink:to="loc_pnw_RegulatoryLiabilityIncludingDeferredChargesCurrent_019e64ef-17ea-78a3-af6d-adfc047a9942" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityNoncurrent_019e64ef-17ea-757e-803b-edc35eca6b55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_019e64ef-17ea-7d5e-9e3c-84cf6832be23" xlink:to="loc_us-gaap_RegulatoryLiabilityNoncurrent_019e64ef-17ea-757e-803b-edc35eca6b55" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RetirementPlansandOtherPostretirementBenefitsScheduleofNetPeriodicBenefitCostsandPortionincludingPortionChargedtoExpenseDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RetirementPlansandOtherPostretirementBenefitsScheduleofNetPeriodicBenefitCostsandPortionincludingPortionChargedtoExpenseDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RetirementPlansandOtherPostretirementBenefitsScheduleofNetPeriodicBenefitCostsandPortionincludingPortionChargedtoExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e64ef-17ea-75a4-a540-33db12253edd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e64ef-17ea-75a4-a540-33db12253edd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7f4d-ad75-3369cfa2f7df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e64ef-17ea-75a4-a540-33db12253edd" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7f4d-ad75-3369cfa2f7df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-7f4d-ad75-3369cfa2f7df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7f4d-ad75-3369cfa2f7df" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-7f4d-ad75-3369cfa2f7df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-77cb-8827-994aaf5e9ac0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7f4d-ad75-3369cfa2f7df" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-77cb-8827-994aaf5e9ac0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019e64ef-17ea-77ce-a7c5-f699f0332c08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-77cb-8827-994aaf5e9ac0" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019e64ef-17ea-77ce-a7c5-f699f0332c08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e64ef-17ea-717b-9af1-e2a0fc238cae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-77cb-8827-994aaf5e9ac0" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e64ef-17ea-717b-9af1-e2a0fc238cae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_019e64ef-17ea-782a-a1cd-d21a069592ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_019e64ef-17ea-782a-a1cd-d21a069592ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_019e64ef-17ea-7b2f-ad74-485505faf440" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_019e64ef-17ea-7b2f-ad74-485505faf440" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_019e64ef-17ea-7d3b-bcb6-076773b40d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_019e64ef-17ea-7b2f-ad74-485505faf440" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_019e64ef-17ea-7d3b-bcb6-076773b40d4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019e64ef-17ea-74a2-a871-9e3a9baa6272" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_019e64ef-17ea-7b2f-ad74-485505faf440" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019e64ef-17ea-74a2-a871-9e3a9baa6272" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DefinedBenefitPlanAmortizationAbstract_019e64ef-17ea-7fb6-9a1a-7ece3ac4511b" xlink:href="pnw-20260630.xsd#pnw_DefinedBenefitPlanAmortizationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:to="loc_pnw_DefinedBenefitPlanAmortizationAbstract_019e64ef-17ea-7fb6-9a1a-7ece3ac4511b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019e64ef-17ea-7aea-afce-89ed9cc2e3bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DefinedBenefitPlanAmortizationAbstract_019e64ef-17ea-7fb6-9a1a-7ece3ac4511b" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019e64ef-17ea-7aea-afce-89ed9cc2e3bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019e64ef-17ea-7678-ab02-e04237dbeba3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DefinedBenefitPlanAmortizationAbstract_019e64ef-17ea-7fb6-9a1a-7ece3ac4511b" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019e64ef-17ea-7678-ab02-e04237dbeba3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e64ef-17ea-71ee-bf4d-797217555d0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e64ef-17ea-71ee-bf4d-797217555d0b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019e64ef-17ea-7763-ae51-8c27d82514a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionAndOtherPostretirementBenefitExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-79fb-88cc-b55a9bc2984f" xlink:to="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019e64ef-17ea-7763-ae51-8c27d82514a0" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/RetirementPlansandOtherPostretirementBenefitsAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#RetirementPlansandOtherPostretirementBenefitsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/RetirementPlansandOtherPostretirementBenefitsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-733d-8d7c-2b7f6677b9e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e64ef-17ea-7cdd-9c9d-0d6bd8f67b18" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-733d-8d7c-2b7f6677b9e9" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e64ef-17ea-7cdd-9c9d-0d6bd8f67b18" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7e75-925b-e7945fef908d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e64ef-17ea-7cdd-9c9d-0d6bd8f67b18" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7e75-925b-e7945fef908d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-7e75-925b-e7945fef908d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7e75-925b-e7945fef908d" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-7e75-925b-e7945fef908d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-78fe-a7da-0690309374eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e64ef-17ea-7e75-925b-e7945fef908d" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-78fe-a7da-0690309374eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019e64ef-17ea-7b47-9494-5b329c7dba30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-78fe-a7da-0690309374eb" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019e64ef-17ea-7b47-9494-5b329c7dba30" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e64ef-17ea-7dd3-b597-7a436a288799" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e64ef-17ea-78fe-a7da-0690309374eb" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e64ef-17ea-7dd3-b597-7a436a288799" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DefinedBenefitPlansEstimatedMinimumFutureEmployerContributionsNextThreeFiscalYears_019e64ef-17ea-7a91-8f8b-8f56947a2c4e" xlink:href="pnw-20260630.xsd#pnw_DefinedBenefitPlansEstimatedMinimumFutureEmployerContributionsNextThreeFiscalYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-733d-8d7c-2b7f6677b9e9" xlink:to="loc_pnw_DefinedBenefitPlansEstimatedMinimumFutureEmployerContributionsNextThreeFiscalYears_019e64ef-17ea-7a91-8f8b-8f56947a2c4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DefinedBenefitPlanRetireeMedicalCostReimbursement_019e64ef-17ea-7dc5-b21d-7fe663e2148d" xlink:href="pnw-20260630.xsd#pnw_DefinedBenefitPlanRetireeMedicalCostReimbursement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e64ef-17ea-733d-8d7c-2b7f6677b9e9" xlink:to="loc_pnw_DefinedBenefitPlanRetireeMedicalCostReimbursement_019e64ef-17ea-7dc5-b21d-7fe663e2148d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/VariableInterestEntitiesAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#VariableInterestEntitiesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/VariableInterestEntitiesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-70f7-85f0-1bfb3d6f57f5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-70f7-85f0-1bfb3d6f57f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-70f7-85f0-1bfb3d6f57f5_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-70f7-85f0-1bfb3d6f57f5" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-70f7-85f0-1bfb3d6f57f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-73e3-9881-7e17fc0168d1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-70f7-85f0-1bfb3d6f57f5" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-73e3-9881-7e17fc0168d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-78d5-a279-fc433f508921" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-73e3-9881-7e17fc0168d1" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-78d5-a279-fc433f508921" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-78c3-820a-e1bb01d00f7b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-78c3-820a-e1bb01d00f7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-78c3-820a-e1bb01d00f7b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-78c3-820a-e1bb01d00f7b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-78c3-820a-e1bb01d00f7b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7723-991e-e198df512118" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-78c3-820a-e1bb01d00f7b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7723-991e-e198df512118" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PinnacleWestCaptiveInsuranceCellMember_019e64ef-18a7-7582-a607-69b796f3540c" xlink:href="pnw-20260630.xsd#pnw_PinnacleWestCaptiveInsuranceCellMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7723-991e-e198df512118" xlink:to="loc_pnw_PinnacleWestCaptiveInsuranceCellMember_019e64ef-18a7-7582-a607-69b796f3540c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-7951-ba67-25875f18ec40" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-7951-ba67-25875f18ec40" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7951-ba67-25875f18ec40_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7951-ba67-25875f18ec40" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7951-ba67-25875f18ec40_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-70cd-a3e0-217d26805991" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7951-ba67-25875f18ec40" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-70cd-a3e0-217d26805991" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-72a8-8c61-449af308664b" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-70cd-a3e0-217d26805991" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-72a8-8c61-449af308664b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_019e64ef-18a7-7de4-8199-52c18ddb05e4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:to="loc_srt_OwnershipAxis_019e64ef-18a7-7de4-8199-52c18ddb05e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_019e64ef-18a7-7de4-8199-52c18ddb05e4_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_019e64ef-18a7-7de4-8199-52c18ddb05e4" xlink:to="loc_srt_OwnershipDomain_019e64ef-18a7-7de4-8199-52c18ddb05e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_019e64ef-18a7-7ad2-8335-6ba4baa40f3a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_019e64ef-18a7-7de4-8199-52c18ddb05e4" xlink:to="loc_srt_OwnershipDomain_019e64ef-18a7-7ad2-8335-6ba4baa40f3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PaloVerdeUnit2Member_019e64ef-18a7-76ad-a978-8c106fb5c0c5" xlink:href="pnw-20260630.xsd#pnw_PaloVerdeUnit2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_019e64ef-18a7-7ad2-8335-6ba4baa40f3a" xlink:to="loc_pnw_PaloVerdeUnit2Member_019e64ef-18a7-76ad-a978-8c106fb5c0c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e64ef-18a7-7073-9a5a-bdb407517469" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:to="loc_srt_RangeAxis_019e64ef-18a7-7073-9a5a-bdb407517469" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e64ef-18a7-7073-9a5a-bdb407517469_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e64ef-18a7-7073-9a5a-bdb407517469" xlink:to="loc_srt_RangeMember_019e64ef-18a7-7073-9a5a-bdb407517469_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e64ef-18a7-7abb-b950-c4a14b3aa485" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e64ef-18a7-7073-9a5a-bdb407517469" xlink:to="loc_srt_RangeMember_019e64ef-18a7-7abb-b950-c4a14b3aa485" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e64ef-18a7-744a-87f5-08b31a35b387" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e64ef-18a7-7abb-b950-c4a14b3aa485" xlink:to="loc_srt_MaximumMember_019e64ef-18a7-744a-87f5-08b31a35b387" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019e64ef-18a7-731b-af5c-04b8fa44801b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-744e-acff-70ba633e2852" xlink:to="loc_srt_StatementScenarioAxis_019e64ef-18a7-731b-af5c-04b8fa44801b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e64ef-18a7-731b-af5c-04b8fa44801b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019e64ef-18a7-731b-af5c-04b8fa44801b" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e64ef-18a7-731b-af5c-04b8fa44801b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e64ef-18a7-7bf2-b281-fb332480ef95" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019e64ef-18a7-731b-af5c-04b8fa44801b" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e64ef-18a7-7bf2-b281-fb332480ef95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019e64ef-18a7-7d3c-90ee-ffef99686fbd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_019e64ef-18a7-7bf2-b281-fb332480ef95" xlink:to="loc_srt_ScenarioForecastMember_019e64ef-18a7-7d3c-90ee-ffef99686fbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-18a7-793c-806f-e5e701e726c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e64ef-18a7-793c-806f-e5e701e726c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_019e64ef-18a7-7eb7-b03c-e43f76d0b336" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_019e64ef-18a7-7eb7-b03c-e43f76d0b336" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVieLessorTrusts_019e64ef-18a7-7ef0-b720-d08e152d2ccc" xlink:href="pnw-20260630.xsd#pnw_NumberOfVieLessorTrusts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_NumberOfVieLessorTrusts_019e64ef-18a7-7ef0-b720-d08e152d2ccc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVIELessorTrustsAcquired_019e64ef-18a7-790b-b955-8655eefdf05a" xlink:href="pnw-20260630.xsd#pnw_NumberOfVIELessorTrustsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_NumberOfVIELessorTrustsAcquired_019e64ef-18a7-790b-b955-8655eefdf05a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVIELessorTrustsTerminated_019e64ef-18a7-75ad-abe2-0151b923bddd" xlink:href="pnw-20260630.xsd#pnw_NumberOfVIELessorTrustsTerminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_NumberOfVIELessorTrustsTerminated_019e64ef-18a7-75ad-abe2-0151b923bddd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityOwnershipPercentage_019e64ef-18a7-74ae-9dd0-d92331a4b62c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_us-gaap_VariableInterestEntityOwnershipPercentage_019e64ef-18a7-74ae-9dd0-d92331a4b62c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_VariableInterestEntityQualitativeOrQuantitativeInformationLeasedInterestPercentage_019e64ef-18a7-7abe-b4ef-f7b268a7b3e3" xlink:href="pnw-20260630.xsd#pnw_VariableInterestEntityQualitativeOrQuantitativeInformationLeasedInterestPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_VariableInterestEntityQualitativeOrQuantitativeInformationLeasedInterestPercentage_019e64ef-18a7-7abe-b4ef-f7b268a7b3e3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AnnualRentalPaymentsSaleLeasebackTransaction_019e64ef-18a7-7d90-93c7-c6adaa6de2ae" xlink:href="pnw-20260630.xsd#pnw_AnnualRentalPaymentsSaleLeasebackTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_AnnualRentalPaymentsSaleLeasebackTransaction_019e64ef-18a7-7d90-93c7-c6adaa6de2ae" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SaleLeasebackTransactionLeaseExtensionPeriod_019e64ef-18a7-7fbb-a1b4-b62c1feda091" xlink:href="pnw-20260630.xsd#pnw_SaleLeasebackTransactionLeaseExtensionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_SaleLeasebackTransactionLeaseExtensionPeriod_019e64ef-18a7-7fbb-a1b4-b62c1feda091" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_VariableInterestEntityEntityInitialLossExposureToNoncontrollingInterestsDuringLeaseExtensionPeriodAmount_019e64ef-18a7-78dc-a35c-6bfd521b36f0" xlink:href="pnw-20260630.xsd#pnw_VariableInterestEntityEntityInitialLossExposureToNoncontrollingInterestsDuringLeaseExtensionPeriodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_VariableInterestEntityEntityInitialLossExposureToNoncontrollingInterestsDuringLeaseExtensionPeriodAmount_019e64ef-18a7-78dc-a35c-6bfd521b36f0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_VariableInterestEntityEntityLossExposureToNoncontrollingInterestsDuringLeaseExtensionPeriodAmount_019e64ef-18a7-7280-b643-d0aca0483bf9" xlink:href="pnw-20260630.xsd#pnw_VariableInterestEntityEntityLossExposureToNoncontrollingInterestsDuringLeaseExtensionPeriodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-7507-a441-53c15ec76279" xlink:to="loc_pnw_VariableInterestEntityEntityLossExposureToNoncontrollingInterestsDuringLeaseExtensionPeriodAmount_019e64ef-18a7-7280-b643-d0aca0483bf9" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/VariableInterestEntitiesScheduleofAmountsRelatingtotheVIEsIncludedinConsolidatedBalanceSheetsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#VariableInterestEntitiesScheduleofAmountsRelatingtotheVIEsIncludedinConsolidatedBalanceSheetsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/VariableInterestEntitiesScheduleofAmountsRelatingtotheVIEsIncludedinConsolidatedBalanceSheetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-77da-8040-2a4efd3b298a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-7490-9c26-de2c70c5c0e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-77da-8040-2a4efd3b298a" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-7490-9c26-de2c70c5c0e9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7e21-9704-79707bc8c020" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-7490-9c26-de2c70c5c0e9" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7e21-9704-79707bc8c020" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7e21-9704-79707bc8c020_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7e21-9704-79707bc8c020" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7e21-9704-79707bc8c020_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7815-a2d1-ea6d17be975e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7e21-9704-79707bc8c020" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7815-a2d1-ea6d17be975e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-72ba-b7eb-c4cbbe8ee3ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7815-a2d1-ea6d17be975e" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-72ba-b7eb-c4cbbe8ee3ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-7e5d-9090-fd3616144b77" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e64ef-18a7-7490-9c26-de2c70c5c0e9" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-7e5d-9090-fd3616144b77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7e5d-9090-fd3616144b77_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7e5d-9090-fd3616144b77" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7e5d-9090-fd3616144b77_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7110-b3e7-209c78706e50" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7e5d-9090-fd3616144b77" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7110-b3e7-209c78706e50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7077-b8f5-d692b96b1b61" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-7110-b3e7-209c78706e50" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7077-b8f5-d692b96b1b61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019e64ef-18a7-7df7-a44f-5663c30f3195" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-77da-8040-2a4efd3b298a" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019e64ef-18a7-7df7-a44f-5663c30f3195" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityNonconsolidatedComparisonOfCarryingAmountOfAssetsAndLiabilitiesToMaximumLossExposureAbstract_019e64ef-18a7-72d1-a103-ae0c5badbaa4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityNonconsolidatedComparisonOfCarryingAmountOfAssetsAndLiabilitiesToMaximumLossExposureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e64ef-18a7-77da-8040-2a4efd3b298a" xlink:to="loc_us-gaap_VariableInterestEntityNonconsolidatedComparisonOfCarryingAmountOfAssetsAndLiabilitiesToMaximumLossExposureAbstract_019e64ef-18a7-72d1-a103-ae0c5badbaa4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_019e64ef-18a7-79e7-a44a-879bc4614588" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityNonconsolidatedComparisonOfCarryingAmountOfAssetsAndLiabilitiesToMaximumLossExposureAbstract_019e64ef-18a7-72d1-a103-ae0c5badbaa4" xlink:to="loc_us-gaap_MinorityInterest_019e64ef-18a7-79e7-a44a-879bc4614588" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DerivativeAccountingAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DerivativeAccountingAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DerivativeAccountingAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:to="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-788c-a8c8-cf1d352ef79b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-788c-a8c8-cf1d352ef79b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-788c-a8c8-cf1d352ef79b_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-788c-a8c8-cf1d352ef79b" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-788c-a8c8-cf1d352ef79b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-76f6-b71e-86879e7bc339" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-788c-a8c8-cf1d352ef79b" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-76f6-b71e-86879e7bc339" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-784f-9c40-16abfec97da8" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-76f6-b71e-86879e7bc339" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-784f-9c40-16abfec97da8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019e64ef-18a7-7528-b2fc-fc250a1c164b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:to="loc_srt_CounterpartyNameAxis_019e64ef-18a7-7528-b2fc-fc250a1c164b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e64ef-18a7-7528-b2fc-fc250a1c164b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019e64ef-18a7-7528-b2fc-fc250a1c164b" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e64ef-18a7-7528-b2fc-fc250a1c164b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e64ef-18a7-724d-829d-cf83b0f3d7da" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019e64ef-18a7-7528-b2fc-fc250a1c164b" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e64ef-18a7-724d-829d-cf83b0f3d7da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_FourCounterpartiesMember_019e64ef-18a7-7493-87c7-190a05318d7c" xlink:href="pnw-20260630.xsd#pnw_FourCounterpartiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e64ef-18a7-724d-829d-cf83b0f3d7da" xlink:to="loc_pnw_FourCounterpartiesMember_019e64ef-18a7-7493-87c7-190a05318d7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e64ef-18a7-756e-b422-5f752955f033" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e64ef-18a7-756e-b422-5f752955f033" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e64ef-18a7-756e-b422-5f752955f033_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e64ef-18a7-756e-b422-5f752955f033" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e64ef-18a7-756e-b422-5f752955f033_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e64ef-18a7-72a1-9102-dcbe68cdcbe0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e64ef-18a7-756e-b422-5f752955f033" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e64ef-18a7-72a1-9102-dcbe68cdcbe0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RiskManagementAssetsMember_019e64ef-18a7-786a-9565-4baf23da05ab" xlink:href="pnw-20260630.xsd#pnw_RiskManagementAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e64ef-18a7-72a1-9102-dcbe68cdcbe0" xlink:to="loc_pnw_RiskManagementAssetsMember_019e64ef-18a7-786a-9565-4baf23da05ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019e64ef-18a7-7272-9142-3201337e3c06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019e64ef-18a7-7272-9142-3201337e3c06" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019e64ef-18a7-7272-9142-3201337e3c06_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019e64ef-18a7-7272-9142-3201337e3c06" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019e64ef-18a7-7272-9142-3201337e3c06_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019e64ef-18a7-71f9-9d83-b2dec46c51cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019e64ef-18a7-7272-9142-3201337e3c06" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019e64ef-18a7-71f9-9d83-b2dec46c51cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CreditConcentrationMember_019e64ef-18a7-7852-b29b-0c0dc3cd6f7f" xlink:href="pnw-20260630.xsd#pnw_CreditConcentrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019e64ef-18a7-71f9-9d83-b2dec46c51cb" xlink:to="loc_pnw_CreditConcentrationMember_019e64ef-18a7-7852-b29b-0c0dc3cd6f7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7fa6-82b5-3b4cd1fde682" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e64ef-18a7-738f-b2d5-7250caff1701" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7fa6-82b5-3b4cd1fde682" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7fa6-82b5-3b4cd1fde682_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7fa6-82b5-3b4cd1fde682" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7fa6-82b5-3b4cd1fde682_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a90-b203-53189d773dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7fa6-82b5-3b4cd1fde682" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a90-b203-53189d773dfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-786a-9c64-b43564f1a9c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a90-b203-53189d773dfc" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-786a-9c64-b43564f1a9c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PercentageOfUnrealizedGainsAndLossesOnCertainDerivativesDeferredForFutureRateTreatment_019e64ef-18a7-7c3d-a999-8dfb2e4766eb" xlink:href="pnw-20260630.xsd#pnw_PercentageOfUnrealizedGainsAndLossesOnCertainDerivativesDeferredForFutureRateTreatment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:to="loc_pnw_PercentageOfUnrealizedGainsAndLossesOnCertainDerivativesDeferredForFutureRateTreatment_019e64ef-18a7-7c3d-a999-8dfb2e4766eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeNumberOfCounterparties_019e64ef-18a7-775d-b0af-ed5a64c4c9f8" xlink:href="pnw-20260630.xsd#pnw_DerivativeNumberOfCounterparties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:to="loc_pnw_DerivativeNumberOfCounterparties_019e64ef-18a7-775d-b0af-ed5a64c4c9f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019e64ef-18a7-749a-a574-05042d91cfa8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019e64ef-18a7-749a-a574-05042d91cfa8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e64ef-18a7-739e-9721-3202a19473de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:to="loc_us-gaap_DerivativeAssets_019e64ef-18a7-739e-9721-3202a19473de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NonDerivativeCreditRiskContractAdditionalCollateralAggregateFairValue_019e64ef-18a7-7af8-ba23-a9bc37aa14ba" xlink:href="pnw-20260630.xsd#pnw_NonDerivativeCreditRiskContractAdditionalCollateralAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7bdf-b69f-b7696be3b008" xlink:to="loc_pnw_NonDerivativeCreditRiskContractAdditionalCollateralAggregateFairValue_019e64ef-18a7-7af8-ba23-a9bc37aa14ba" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DerivativeAccountingScheduleofOutstandingGrossNotionalAmountsOutstandingDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DerivativeAccountingScheduleofOutstandingGrossNotionalAmountsOutstandingDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DerivativeAccountingScheduleofOutstandingGrossNotionalAmountsOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7071-85a3-82c518854143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e64ef-18a7-7f4d-a24f-3b87d0b0d3e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7071-85a3-82c518854143" xlink:to="loc_us-gaap_DerivativeTable_019e64ef-18a7-7f4d-a24f-3b87d0b0d3e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7665-ad22-873b983166d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e64ef-18a7-7f4d-a24f-3b87d0b0d3e0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7665-ad22-873b983166d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7665-ad22-873b983166d1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7665-ad22-873b983166d1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7665-ad22-873b983166d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a9d-ac27-c42badec87c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7665-ad22-873b983166d1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a9d-ac27-c42badec87c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-74d1-afbe-cce90e2792b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a9d-ac27-c42badec87c2" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-74d1-afbe-cce90e2792b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotionalAmountOfDerivativesAbstract_019e64ef-18a7-71b8-827a-be4b7f0086b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotionalAmountOfDerivativesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e64ef-18a7-7071-85a3-82c518854143" xlink:to="loc_us-gaap_NotionalAmountOfDerivativesAbstract_019e64ef-18a7-71b8-827a-be4b7f0086b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_019e64ef-18a7-703b-8203-bf166cbc118b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NotionalAmountOfDerivativesAbstract_019e64ef-18a7-71b8-827a-be4b7f0086b2" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_019e64ef-18a7-703b-8203-bf166cbc118b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_019e64ef-18a7-7ee3-8639-7daf1e9f4ae4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NotionalAmountOfDerivativesAbstract_019e64ef-18a7-71b8-827a-be4b7f0086b2" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_019e64ef-18a7-7ee3-8639-7daf1e9f4ae4" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DerivativeAccountingScheduleofGainsandLossesfromDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DerivativeAccountingScheduleofGainsandLossesfromDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DerivativeAccountingScheduleofGainsandLossesfromDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e64ef-18a7-7ffd-8e78-3ec32137ccab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e64ef-18a7-72f7-9cad-ee17b5d5dfd0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e64ef-18a7-7ffd-8e78-3ec32137ccab" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e64ef-18a7-72f7-9cad-ee17b5d5dfd0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7c45-9686-13d12f1d3779" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e64ef-18a7-72f7-9cad-ee17b5d5dfd0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7c45-9686-13d12f1d3779" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7c45-9686-13d12f1d3779_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7c45-9686-13d12f1d3779" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7c45-9686-13d12f1d3779_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7e28-a7b4-10433268d94a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7c45-9686-13d12f1d3779" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7e28-a7b4-10433268d94a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7b49-953c-8645bb9117a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7e28-a7b4-10433268d94a" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7b49-953c-8645bb9117a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e64ef-18a7-73a7-b9b7-9504412efcc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e64ef-18a7-72f7-9cad-ee17b5d5dfd0" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e64ef-18a7-73a7-b9b7-9504412efcc9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e64ef-18a7-73a7-b9b7-9504412efcc9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e64ef-18a7-73a7-b9b7-9504412efcc9" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e64ef-18a7-73a7-b9b7-9504412efcc9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e64ef-18a7-79e0-a59e-ad88698200d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e64ef-18a7-73a7-b9b7-9504412efcc9" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e64ef-18a7-79e0-a59e-ad88698200d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e64ef-18a7-7645-ae42-ed1e00c76802" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e64ef-18a7-79e0-a59e-ad88698200d6" xlink:to="loc_us-gaap_NondesignatedMember_019e64ef-18a7-7645-ae42-ed1e00c76802" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_019e64ef-18a7-75f1-a9da-9f2cc84c7d2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeGainLossOnDerivativeNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e64ef-18a7-7ffd-8e78-3ec32137ccab" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_019e64ef-18a7-75f1-a9da-9f2cc84c7d2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e64ef-18a7-7d84-b06c-3660027fe0ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeGainLossOnDerivativeNetAbstract_019e64ef-18a7-75f1-a9da-9f2cc84c7d2b" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e64ef-18a7-7d84-b06c-3660027fe0ee" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DerivativeAccountingScheduleofDerivativeInstrumentsintheBalanceSheetDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DerivativeAccountingScheduleofDerivativeInstrumentsintheBalanceSheetDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DerivativeAccountingScheduleofDerivativeInstrumentsintheBalanceSheetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:href="pnw-20260630.xsd#pnw_OffsettingAssetsAndLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:href="pnw-20260630.xsd#pnw_OffsettingAssetsAndLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a18-a5cb-74d4d60e9445_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a18-a5cb-74d4d60e9445_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d30-a75e-adaed6b5c910" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d30-a75e-adaed6b5c910" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-766f-b34b-e9cc958a3858" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d30-a75e-adaed6b5c910" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-766f-b34b-e9cc958a3858" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e64ef-18a7-7bc8-b04b-d1b7c2c7d74d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e64ef-18a7-7bc8-b04b-d1b7c2c7d74d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e64ef-18a7-75f2-8304-f90ecf0dd3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e64ef-18a7-75f2-8304-f90ecf0dd3e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_019e64ef-18a7-74fa-8c9f-00525b7a9dde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_019e64ef-18a7-74fa-8c9f-00525b7a9dde" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e64ef-18a7-7f9b-9796-1f07cd990599" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e64ef-18a7-7f9b-9796-1f07cd990599" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetNotSubjectToMasterNettingArrangement_019e64ef-18a7-7ec9-90fc-1d611bcef5ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeAssetNotSubjectToMasterNettingArrangement_019e64ef-18a7-7ec9-90fc-1d611bcef5ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e64ef-18a7-7f65-b421-6b14524d1a6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeAssets_019e64ef-18a7-7f65-b421-6b14524d1a6e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e64ef-18a7-7676-a5ab-3fd655bb85bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e64ef-18a7-7676-a5ab-3fd655bb85bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_019e64ef-18a7-722e-97bb-b8e7b233259d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_019e64ef-18a7-722e-97bb-b8e7b233259d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-788c-a6ed-9a30196c73bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-788c-a6ed-9a30196c73bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNotSubjectToMasterNettingArrangement_019e64ef-18a7-7d34-972c-bb8abb531491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeLiabilityNotSubjectToMasterNettingArrangement_019e64ef-18a7-7d34-972c-bb8abb531491" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-756f-a6d5-2a3460498ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-756f-a6d5-2a3460498ed8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:href="pnw-20260630.xsd#pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityFairValueGrossAssetLiability_019e64ef-18a7-7714-aab7-643899e2a832" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityFairValueGrossAssetLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityFairValueGrossAssetLiability_019e64ef-18a7-7714-aab7-643899e2a832" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityFairValueGrossLiabilityAssetAndObligationToReturnAndRightToReclaimCashOffset_019e64ef-18a7-77e0-86da-b2216b05a570" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityFairValueGrossLiabilityAssetAndObligationToReturnAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityFairValueGrossLiabilityAssetAndObligationToReturnAndRightToReclaimCashOffset_019e64ef-18a7-77e0-86da-b2216b05a570" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityFairValueAmountNotOffsetAgainstCollateral_019e64ef-18a7-7173-b277-7bcbb462b6e3" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityFairValueAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityFairValueAmountNotOffsetAgainstCollateral_019e64ef-18a7-7173-b277-7bcbb462b6e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-782d-bd1d-2b0c3513465b" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-782d-bd1d-2b0c3513465b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e64ef-18a7-778f-ac77-363351b73b56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e64ef-18a7-778f-ac77-363351b73b56" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DerivativeAccountingScheduleofDerivativeInstrumentsintheBalanceSheetDetails_1" xlink:type="simple" xlink:href="pnw-20260630.xsd#DerivativeAccountingScheduleofDerivativeInstrumentsintheBalanceSheetDetails_1"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DerivativeAccountingScheduleofDerivativeInstrumentsintheBalanceSheetDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:href="pnw-20260630.xsd#pnw_OffsettingAssetsAndLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:href="pnw-20260630.xsd#pnw_OffsettingAssetsAndLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesTable_019e64ef-18a7-72c2-bfc1-a9b98c7e550b" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a18-a5cb-74d4d60e9445_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7a18-a5cb-74d4d60e9445_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d30-a75e-adaed6b5c910" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7a18-a5cb-74d4d60e9445" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d30-a75e-adaed6b5c910" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-766f-b34b-e9cc958a3858" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d30-a75e-adaed6b5c910" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-766f-b34b-e9cc958a3858" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e64ef-18a7-75f2-8304-f90ecf0dd3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e64ef-18a7-75f2-8304-f90ecf0dd3e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_019e64ef-18a7-74fa-8c9f-00525b7a9dde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_019e64ef-18a7-74fa-8c9f-00525b7a9dde" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e64ef-18a7-7f9b-9796-1f07cd990599" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e64ef-18a7-7f9b-9796-1f07cd990599" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetNotSubjectToMasterNettingArrangement_019e64ef-18a7-7ec9-90fc-1d611bcef5ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeAssetNotSubjectToMasterNettingArrangement_019e64ef-18a7-7ec9-90fc-1d611bcef5ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e64ef-18a7-7f65-b421-6b14524d1a6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019e64ef-18a7-744b-a5ea-430618705fb7" xlink:to="loc_us-gaap_DerivativeAssets_019e64ef-18a7-7f65-b421-6b14524d1a6e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e64ef-18a7-7676-a5ab-3fd655bb85bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e64ef-18a7-7676-a5ab-3fd655bb85bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_019e64ef-18a7-722e-97bb-b8e7b233259d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_019e64ef-18a7-722e-97bb-b8e7b233259d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-788c-a6ed-9a30196c73bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-788c-a6ed-9a30196c73bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNotSubjectToMasterNettingArrangement_019e64ef-18a7-7d34-972c-bb8abb531491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeLiabilityNotSubjectToMasterNettingArrangement_019e64ef-18a7-7d34-972c-bb8abb531491" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-756f-a6d5-2a3460498ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019e64ef-18a7-7b1d-ac4a-c5ca07c0c059" xlink:to="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-756f-a6d5-2a3460498ed8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:href="pnw-20260630.xsd#pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingAssetsAndLiabilitiesLineItems_019e64ef-18a7-79bd-81ac-640b68e234c2" xlink:to="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityFairValueGrossAssetLiability_019e64ef-18a7-7714-aab7-643899e2a832" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityFairValueGrossAssetLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityFairValueGrossAssetLiability_019e64ef-18a7-7714-aab7-643899e2a832" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityFairValueGrossLiabilityAssetAndObligationToReturnAndRightToReclaimCashOffset_019e64ef-18a7-77e0-86da-b2216b05a570" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityFairValueGrossLiabilityAssetAndObligationToReturnAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityFairValueGrossLiabilityAssetAndObligationToReturnAndRightToReclaimCashOffset_019e64ef-18a7-77e0-86da-b2216b05a570" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityFairValueAmountNotOffsetAgainstCollateral_019e64ef-18a7-7173-b277-7bcbb462b6e3" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityFairValueAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityFairValueAmountNotOffsetAgainstCollateral_019e64ef-18a7-7173-b277-7bcbb462b6e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DerivativeAssetLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-782d-bd1d-2b0c3513465b" xlink:href="pnw-20260630.xsd#pnw_DerivativeAssetLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_pnw_DerivativeAssetLiabilityAmountNotOffsetAgainstCollateral_019e64ef-18a7-782d-bd1d-2b0c3513465b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e64ef-18a7-778f-ac77-363351b73b56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_OffsettingDerivativeAssetsLiabilitiesNetAbstract_019e64ef-18a7-79f0-a60d-be5ffc35c62e" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e64ef-18a7-778f-ac77-363351b73b56" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/DerivativeAccountingScheduleofCreditRiskandRelatedContingentFeaturesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#DerivativeAccountingScheduleofCreditRiskandRelatedContingentFeaturesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/DerivativeAccountingScheduleofCreditRiskandRelatedContingentFeaturesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019e64ef-18a7-71ac-b234-20296191abbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e64ef-18a7-77a7-afb8-0a4644e780a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e64ef-18a7-71ac-b234-20296191abbb" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e64ef-18a7-77a7-afb8-0a4644e780a3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7121-827e-ac870b06e8dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e64ef-18a7-77a7-afb8-0a4644e780a3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7121-827e-ac870b06e8dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7121-827e-ac870b06e8dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7121-827e-ac870b06e8dd" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7121-827e-ac870b06e8dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7922-ab6a-acc99dd468fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7121-827e-ac870b06e8dd" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7922-ab6a-acc99dd468fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7fff-90b7-1ebcf09aec8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7922-ab6a-acc99dd468fa" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7fff-90b7-1ebcf09aec8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCreditRiskRelatedContingentFeaturesAbstract_019e64ef-18a7-77ca-9bb5-f2ab4c592c18" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCreditRiskRelatedContingentFeaturesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e64ef-18a7-71ac-b234-20296191abbb" xlink:to="loc_us-gaap_DerivativeCreditRiskRelatedContingentFeaturesAbstract_019e64ef-18a7-77ca-9bb5-f2ab4c592c18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNetLiabilityPositionAggregateFairValue_019e64ef-18a7-7355-8d2d-5a82e4cdacce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNetLiabilityPositionAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeCreditRiskRelatedContingentFeaturesAbstract_019e64ef-18a7-77ca-9bb5-f2ab4c592c18" xlink:to="loc_us-gaap_DerivativeNetLiabilityPositionAggregateFairValue_019e64ef-18a7-7355-8d2d-5a82e4cdacce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalCollateralAggregateFairValue_019e64ef-18a7-7fc2-810e-3f1c9906e7bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalCollateralAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeCreditRiskRelatedContingentFeaturesAbstract_019e64ef-18a7-77ca-9bb5-f2ab4c592c18" xlink:to="loc_us-gaap_AdditionalCollateralAggregateFairValue_019e64ef-18a7-7fc2-810e-3f1c9906e7bc" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:href="pnw-20260630.xsd#pnw_ScheduleOfCommitmentsAndContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:href="pnw-20260630.xsd#pnw_ScheduleOfCommitmentsAndContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-7146-9fc3-36c8e821f591" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-7146-9fc3-36c8e821f591" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7146-9fc3-36c8e821f591_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7146-9fc3-36c8e821f591" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7146-9fc3-36c8e821f591_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7175-9827-e6a10a0c69a7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7146-9fc3-36c8e821f591" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7175-9827-e6a10a0c69a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-76d3-8edb-f0d23e6cecfc" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-7175-9827-e6a10a0c69a7" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-76d3-8edb-f0d23e6cecfc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NavajoTransitionalEnergyCompanyLLCMember_019e64ef-18a7-706c-a13f-bfdd0bd53b4e" xlink:href="pnw-20260630.xsd#pnw_NavajoTransitionalEnergyCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-7175-9827-e6a10a0c69a7" xlink:to="loc_pnw_NavajoTransitionalEnergyCompanyLLCMember_019e64ef-18a7-706c-a13f-bfdd0bd53b4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019e64ef-18a7-7954-a9ee-618948d650c1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_srt_LitigationCaseAxis_019e64ef-18a7-7954-a9ee-618948d650c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e64ef-18a7-7954-a9ee-618948d650c1_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019e64ef-18a7-7954-a9ee-618948d650c1" xlink:to="loc_srt_LitigationCaseTypeDomain_019e64ef-18a7-7954-a9ee-618948d650c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e64ef-18a7-7f56-98c0-19459acc34d7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019e64ef-18a7-7954-a9ee-618948d650c1" xlink:to="loc_srt_LitigationCaseTypeDomain_019e64ef-18a7-7f56-98c0-19459acc34d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyandPaloVerdeOwnersvs.UnitedStatesDepartmentofEnergySpentNuclearFuelandWasteDisposalMember_019e64ef-18a7-7612-a1b2-2c89adf88ad6" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyandPaloVerdeOwnersvs.UnitedStatesDepartmentofEnergySpentNuclearFuelandWasteDisposalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019e64ef-18a7-7f56-98c0-19459acc34d7" xlink:to="loc_pnw_ArizonaPublicServiceCompanyandPaloVerdeOwnersvs.UnitedStatesDepartmentofEnergySpentNuclearFuelandWasteDisposalMember_019e64ef-18a7-7612-a1b2-2c89adf88ad6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-18a7-71db-a139-59d27adc9ab3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-18a7-71db-a139-59d27adc9ab3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e64ef-18a7-71db-a139-59d27adc9ab3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-18a7-71db-a139-59d27adc9ab3" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e64ef-18a7-71db-a139-59d27adc9ab3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e64ef-18a7-7d55-985b-e5dbb843ec1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e64ef-18a7-71db-a139-59d27adc9ab3" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e64ef-18a7-7d55-985b-e5dbb843ec1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ContaminatedGroundwaterWellsMember_019e64ef-18a7-7c14-9064-13e02a58e63c" xlink:href="pnw-20260630.xsd#pnw_ContaminatedGroundwaterWellsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e64ef-18a7-7d55-985b-e5dbb843ec1d" xlink:to="loc_pnw_ContaminatedGroundwaterWellsMember_019e64ef-18a7-7c14-9064-13e02a58e63c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019e64ef-18a7-79dc-8202-b50317ced98a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_us-gaap_LitigationStatusAxis_019e64ef-18a7-79dc-8202-b50317ced98a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e64ef-18a7-79dc-8202-b50317ced98a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019e64ef-18a7-79dc-8202-b50317ced98a" xlink:to="loc_us-gaap_LitigationStatusDomain_019e64ef-18a7-79dc-8202-b50317ced98a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e64ef-18a7-7c1f-93d5-c134f8ebb6d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019e64ef-18a7-79dc-8202-b50317ced98a" xlink:to="loc_us-gaap_LitigationStatusDomain_019e64ef-18a7-7c1f-93d5-c134f8ebb6d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019e64ef-18a7-7e1a-baa6-d3bf06832e4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019e64ef-18a7-7c1f-93d5-c134f8ebb6d5" xlink:to="loc_us-gaap_PendingLitigationMember_019e64ef-18a7-7e1a-baa6-d3bf06832e4d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e64ef-18a7-7c61-95be-f6b205147b60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_us-gaap_CreditFacilityAxis_019e64ef-18a7-7c61-95be-f6b205147b60" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e64ef-18a7-7c61-95be-f6b205147b60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e64ef-18a7-7c61-95be-f6b205147b60" xlink:to="loc_us-gaap_CreditFacilityDomain_019e64ef-18a7-7c61-95be-f6b205147b60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e64ef-18a7-71d9-b823-fd74e0104744" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e64ef-18a7-7c61-95be-f6b205147b60" xlink:to="loc_us-gaap_CreditFacilityDomain_019e64ef-18a7-71d9-b823-fd74e0104744" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019e64ef-18a7-78d7-984f-b1dde779e17b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e64ef-18a7-71d9-b823-fd74e0104744" xlink:to="loc_us-gaap_LetterOfCreditMember_019e64ef-18a7-78d7-984f-b1dde779e17b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7675-992e-9129bbe78c36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7675-992e-9129bbe78c36" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7675-992e-9129bbe78c36_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7675-992e-9129bbe78c36" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7675-992e-9129bbe78c36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-71ca-aa8d-395f3ec33835" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7675-992e-9129bbe78c36" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-71ca-aa8d-395f3ec33835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SuretyBondsExpiringIn2028Member_019e64ef-18a7-7db5-a412-8cd91512ceae" xlink:href="pnw-20260630.xsd#pnw_SuretyBondsExpiringIn2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-71ca-aa8d-395f3ec33835" xlink:to="loc_pnw_SuretyBondsExpiringIn2028Member_019e64ef-18a7-7db5-a412-8cd91512ceae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantAxis_019e64ef-18a7-7828-b779-722877e4533b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_JointlyOwnedUtilityPlantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesTable_019e64ef-18a7-755e-9e4e-b835ebff225a" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantAxis_019e64ef-18a7-7828-b779-722877e4533b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_019e64ef-18a7-7828-b779-722877e4533b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_019e64ef-18a7-7828-b779-722877e4533b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_019e64ef-18a7-7828-b779-722877e4533b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_019e64ef-18a7-7e1a-83ea-8ebdc42cee41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_019e64ef-18a7-7828-b779-722877e4533b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_019e64ef-18a7-7e1a-83ea-8ebdc42cee41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_FourCornersMember_019e64ef-18a7-728d-8919-da477d169543" xlink:href="pnw-20260630.xsd#pnw_FourCornersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantDomain_019e64ef-18a7-7e1a-83ea-8ebdc42cee41" xlink:to="loc_pnw_FourCornersMember_019e64ef-18a7-728d-8919-da477d169543" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_GainContingencyNewClaimsFiledNumber_019e64ef-18a7-73d9-a201-8ef1870e04d8" xlink:href="pnw-20260630.xsd#pnw_GainContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_GainContingencyNewClaimsFiledNumber_019e64ef-18a7-73d9-a201-8ef1870e04d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedFromOtherParty_019e64ef-18a7-701b-a1d6-e5b3684f050a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedFromOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedFromOtherParty_019e64ef-18a7-701b-a1d6-e5b3684f050a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MaximumInsuranceCoveragePerIncident_019e64ef-18a7-71d8-a417-7aaf46c2c91e" xlink:href="pnw-20260630.xsd#pnw_MaximumInsuranceCoveragePerIncident"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_MaximumInsuranceCoveragePerIncident_019e64ef-18a7-71d8-a417-7aaf46c2c91e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MaximumAvailableNuclearLiabilityInsurance_019e64ef-18a7-768c-9580-a7c6f22cf500" xlink:href="pnw-20260630.xsd#pnw_MaximumAvailableNuclearLiabilityInsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_MaximumAvailableNuclearLiabilityInsurance_019e64ef-18a7-768c-9580-a7c6f22cf500" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_RemainingNuclearLiabilityInsuranceThroughMandatoryIndustryWideRetrospectiveAssessmentProgram_019e64ef-18a7-705a-aa78-69e2b1536e1e" xlink:href="pnw-20260630.xsd#pnw_RemainingNuclearLiabilityInsuranceThroughMandatoryIndustryWideRetrospectiveAssessmentProgram"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_RemainingNuclearLiabilityInsuranceThroughMandatoryIndustryWideRetrospectiveAssessmentProgram_019e64ef-18a7-705a-aa78-69e2b1536e1e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MaximumAssessmentPerReactorForEachNuclearIncident_019e64ef-18a7-7599-8e61-84a28ee10a0b" xlink:href="pnw-20260630.xsd#pnw_MaximumAssessmentPerReactorForEachNuclearIncident"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_MaximumAssessmentPerReactorForEachNuclearIncident_019e64ef-18a7-7599-8e61-84a28ee10a0b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AnnualLimitPerIncidentWithRespectToMaximumAssessment_019e64ef-18a7-78df-b47d-54f4263b7cde" xlink:href="pnw-20260630.xsd#pnw_AnnualLimitPerIncidentWithRespectToMaximumAssessment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_AnnualLimitPerIncidentWithRespectToMaximumAssessment_019e64ef-18a7-78df-b47d-54f4263b7cde" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVIELessorTrusts_019e64ef-18a7-7924-b469-f5bb2615cebd" xlink:href="pnw-20260630.xsd#pnw_NumberOfVIELessorTrusts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_NumberOfVIELessorTrusts_019e64ef-18a7-7924-b469-f5bb2615cebd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MaximumPotentialRetrospectiveAssessmentPerIncident_019e64ef-18a7-7ec7-905a-bf0287459869" xlink:href="pnw-20260630.xsd#pnw_MaximumPotentialRetrospectiveAssessmentPerIncident"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_MaximumPotentialRetrospectiveAssessmentPerIncident_019e64ef-18a7-7ec7-905a-bf0287459869" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AnnualPaymentLimitationWithRespectToMaximumPotentialRetrospectiveAssessment_019e64ef-18a7-7eed-b910-2ad4fe37b1f5" xlink:href="pnw-20260630.xsd#pnw_AnnualPaymentLimitationWithRespectToMaximumPotentialRetrospectiveAssessment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_AnnualPaymentLimitationWithRespectToMaximumPotentialRetrospectiveAssessment_019e64ef-18a7-7eed-b910-2ad4fe37b1f5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AllRiskInsuranceForPropertyDamageAndDecontaminationAtPaloVerde_019e64ef-18a7-7c7b-ac99-15f5833e2a3d" xlink:href="pnw-20260630.xsd#pnw_AllRiskInsuranceForPropertyDamageAndDecontaminationAtPaloVerde"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_AllRiskInsuranceForPropertyDamageAndDecontaminationAtPaloVerde_019e64ef-18a7-7c7b-ac99-15f5833e2a3d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MaximumAmountthatCouldbeIncurredunderRetrospectiveAssessmentofNEILPolicies_019e64ef-18a7-7245-9729-76ce7370cb1b" xlink:href="pnw-20260630.xsd#pnw_MaximumAmountthatCouldbeIncurredunderRetrospectiveAssessmentofNEILPolicies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_MaximumAmountthatCouldbeIncurredunderRetrospectiveAssessmentofNEILPolicies_019e64ef-18a7-7245-9729-76ce7370cb1b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CollateralAssuranceBasedOnRatingTriggers_019e64ef-18a7-7624-b19f-6abc442a74d4" xlink:href="pnw-20260630.xsd#pnw_CollateralAssuranceBasedOnRatingTriggers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_CollateralAssuranceBasedOnRatingTriggers_019e64ef-18a7-7624-b19f-6abc442a74d4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PeriodToProvideCollateralAssuranceBasedOnRatingTriggers_019e64ef-18a7-7484-8fd2-646cc19a6670" xlink:href="pnw-20260630.xsd#pnw_PeriodToProvideCollateralAssuranceBasedOnRatingTriggers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_PeriodToProvideCollateralAssuranceBasedOnRatingTriggers_019e64ef-18a7-7484-8fd2-646cc19a6670" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LossContingencyNumberOfPowerPlantOperators_019e64ef-18a7-7b67-8729-45de9f21b370" xlink:href="pnw-20260630.xsd#pnw_LossContingencyNumberOfPowerPlantOperators"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_LossContingencyNumberOfPowerPlantOperators_019e64ef-18a7-7b67-8729-45de9f21b370" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_IncreaseDecreaseInUnrecordedUnconditionalPurchaseObligation_019e64ef-18a7-770a-8f85-0e3dc73f0521" xlink:href="pnw-20260630.xsd#pnw_IncreaseDecreaseInUnrecordedUnconditionalPurchaseObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_IncreaseDecreaseInUnrecordedUnconditionalPurchaseObligation_019e64ef-18a7-770a-8f85-0e3dc73f0521" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CostsRelatedToInvestigationAndStudyUnderSuperfundSite_019e64ef-18a7-7385-88e0-267c1191c0ce" xlink:href="pnw-20260630.xsd#pnw_CostsRelatedToInvestigationAndStudyUnderSuperfundSite"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_CostsRelatedToInvestigationAndStudyUnderSuperfundSite_019e64ef-18a7-7385-88e0-267c1191c0ce" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019e64ef-18a7-7938-88b3-5e048e89fbdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019e64ef-18a7-7938-88b3-5e048e89fbdd" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CostsRelatedToOversightAndRemedialInvestigationOfSuperfundSite_019e64ef-18a7-740f-9836-85f585e5d28d" xlink:href="pnw-20260630.xsd#pnw_CostsRelatedToOversightAndRemedialInvestigationOfSuperfundSite"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_CostsRelatedToOversightAndRemedialInvestigationOfSuperfundSite_019e64ef-18a7-740f-9836-85f585e5d28d" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019e64ef-18a7-73d2-a3b3-d82cdb5888a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019e64ef-18a7-73d2-a3b3-d82cdb5888a2" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SuretyBondsExpiringAmount_019e64ef-18a7-7d7c-be6a-2abd3ce4bb5c" xlink:href="pnw-20260630.xsd#pnw_SuretyBondsExpiringAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_SuretyBondsExpiringAmount_019e64ef-18a7-7d7c-be6a-2abd3ce4bb5c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AssetPurchaseAgreementOptiontoPurchaseOwnershipInterestPercentage_019e64ef-18a7-7c9d-93c4-946273d6e883" xlink:href="pnw-20260630.xsd#pnw_AssetPurchaseAgreementOptiontoPurchaseOwnershipInterestPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_AssetPurchaseAgreementOptiontoPurchaseOwnershipInterestPercentage_019e64ef-18a7-7c9d-93c4-946273d6e883" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ProductionTaxCreditGuarantees_019e64ef-18a7-7dbf-bf21-bece98734d0b" xlink:href="pnw-20260630.xsd#pnw_ProductionTaxCreditGuarantees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ScheduleOfCommitmentsAndContingenciesLineItems_019e64ef-18a7-7a1a-988d-6821d3a769cb" xlink:to="loc_pnw_ProductionTaxCreditGuarantees_019e64ef-18a7-7dbf-bf21-bece98734d0b" xlink:type="arc" order="22"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/OtherIncomeandOtherExpenseDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#OtherIncomeandOtherExpenseDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/OtherIncomeandOtherExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ComponentofOtherIncomeandOtherExpenseNonoperatingLineItems_019e64ef-18a7-7d86-a4bd-6da5dd97bd4d" xlink:href="pnw-20260630.xsd#pnw_ComponentofOtherIncomeandOtherExpenseNonoperatingLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ComponentOfOtherIncomeAndOtherExpenseNonoperatingTable_019e64ef-18a7-7349-8741-98ce8e839c0a" xlink:href="pnw-20260630.xsd#pnw_ComponentOfOtherIncomeAndOtherExpenseNonoperatingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnw_ComponentofOtherIncomeandOtherExpenseNonoperatingLineItems_019e64ef-18a7-7d86-a4bd-6da5dd97bd4d" xlink:to="loc_pnw_ComponentOfOtherIncomeAndOtherExpenseNonoperatingTable_019e64ef-18a7-7349-8741-98ce8e839c0a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-731f-9c98-8774cfd41e03" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnw_ComponentOfOtherIncomeAndOtherExpenseNonoperatingTable_019e64ef-18a7-7349-8741-98ce8e839c0a" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-731f-9c98-8774cfd41e03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-731f-9c98-8774cfd41e03_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-731f-9c98-8774cfd41e03" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-731f-9c98-8774cfd41e03_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7853-b818-cb85d959ea8a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-731f-9c98-8774cfd41e03" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7853-b818-cb85d959ea8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-79a2-8183-db4fe78648fa" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-7853-b818-cb85d959ea8a" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-79a2-8183-db4fe78648fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncomeDisclosureNonoperatingAbstract_019e64ef-18a7-72a0-b7d4-869e403ad9ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIncomeDisclosureNonoperatingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ComponentofOtherIncomeandOtherExpenseNonoperatingLineItems_019e64ef-18a7-7d86-a4bd-6da5dd97bd4d" xlink:to="loc_us-gaap_OtherIncomeDisclosureNonoperatingAbstract_019e64ef-18a7-72a0-b7d4-869e403ad9ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_019e64ef-18a7-702e-a565-36bd47d95c19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeDisclosureNonoperatingAbstract_019e64ef-18a7-72a0-b7d4-869e403ad9ac" xlink:to="loc_us-gaap_InvestmentIncomeInterest_019e64ef-18a7-702e-a565-36bd47d95c19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_019e64ef-18a7-75ac-9e51-37c29769c891" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeDisclosureNonoperatingAbstract_019e64ef-18a7-72a0-b7d4-869e403ad9ac" xlink:to="loc_us-gaap_GainLossOnInvestments_019e64ef-18a7-75ac-9e51-37c29769c891" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MiscellaneousOtherNonOperatingIncome_019e64ef-18a7-7b39-90d7-475225820286" xlink:href="pnw-20260630.xsd#pnw_MiscellaneousOtherNonOperatingIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeDisclosureNonoperatingAbstract_019e64ef-18a7-72a0-b7d4-869e403ad9ac" xlink:to="loc_pnw_MiscellaneousOtherNonOperatingIncome_019e64ef-18a7-7b39-90d7-475225820286" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncome_019e64ef-18a7-7d0a-b453-86ff8af87186" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeDisclosureNonoperatingAbstract_019e64ef-18a7-72a0-b7d4-869e403ad9ac" xlink:to="loc_us-gaap_OtherNonoperatingIncome_019e64ef-18a7-7d0a-b453-86ff8af87186" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenseDisclosureNonoperatingAbstract_019e64ef-18a7-73e5-925e-9eeeea124847" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherExpenseDisclosureNonoperatingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ComponentofOtherIncomeandOtherExpenseNonoperatingLineItems_019e64ef-18a7-7d86-a4bd-6da5dd97bd4d" xlink:to="loc_us-gaap_OtherExpenseDisclosureNonoperatingAbstract_019e64ef-18a7-73e5-925e-9eeeea124847" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NonOperatingCosts_019e64ef-18a7-73df-b436-6a3a1a6d9691" xlink:href="pnw-20260630.xsd#pnw_NonOperatingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherExpenseDisclosureNonoperatingAbstract_019e64ef-18a7-73e5-925e-9eeeea124847" xlink:to="loc_pnw_NonOperatingCosts_019e64ef-18a7-73df-b436-6a3a1a6d9691" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_MiscellaneousOtherNonOperatingExpense_019e64ef-18a7-7b7f-9825-10ef9f5ceab2" xlink:href="pnw-20260630.xsd#pnw_MiscellaneousOtherNonOperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherExpenseDisclosureNonoperatingAbstract_019e64ef-18a7-73e5-925e-9eeeea124847" xlink:to="loc_pnw_MiscellaneousOtherNonOperatingExpense_019e64ef-18a7-7b7f-9825-10ef9f5ceab2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_019e64ef-18a7-7f8b-8315-49688228de7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherExpenseDisclosureNonoperatingAbstract_019e64ef-18a7-73e5-925e-9eeeea124847" xlink:to="loc_us-gaap_OtherNonoperatingExpense_019e64ef-18a7-7f8b-8315-49688228de7a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/CommonStockEquityandEarningsPerShareAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#CommonStockEquityandEarningsPerShareAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/CommonStockEquityandEarningsPerShareAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-75d0-b2ee-b4593650a39d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-75d0-b2ee-b4593650a39d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-75d0-b2ee-b4593650a39d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-75d0-b2ee-b4593650a39d" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-75d0-b2ee-b4593650a39d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-79eb-8ddf-91575d3f51f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-75d0-b2ee-b4593650a39d" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-79eb-8ddf-91575d3f51f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ATMProgramMember_019e64ef-18a7-7190-b5db-5ca6df635a60" xlink:href="pnw-20260630.xsd#pnw_ATMProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-79eb-8ddf-91575d3f51f4" xlink:to="loc_pnw_ATMProgramMember_019e64ef-18a7-7190-b5db-5ca6df635a60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ThirteenAtTheMarketOfferingsMember_019f26ba-3e16-7f5c-aa0c-f983fe2fc4c6" xlink:href="pnw-20260630.xsd#pnw_ThirteenAtTheMarketOfferingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-79eb-8ddf-91575d3f51f4" xlink:to="loc_pnw_ThirteenAtTheMarketOfferingsMember_019f26ba-3e16-7f5c-aa0c-f983fe2fc4c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_FourteenthATMForwardSaleAgreementMember_019f26bb-c464-7c75-afc7-10c4f698b73d" xlink:href="pnw-20260630.xsd#pnw_FourteenthATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-79eb-8ddf-91575d3f51f4" xlink:to="loc_pnw_FourteenthATMForwardSaleAgreementMember_019f26bb-c464-7c75-afc7-10c4f698b73d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7be9-bf77-0dae475adb8e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7be9-bf77-0dae475adb8e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7be9-bf77-0dae475adb8e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7be9-bf77-0dae475adb8e" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7be9-bf77-0dae475adb8e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7d7d-b990-a249f7f0d919" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7be9-bf77-0dae475adb8e" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7d7d-b990-a249f7f0d919" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_019e64ef-18a7-7be4-8630-a9600e717f6c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7d7d-b990-a249f7f0d919" xlink:to="loc_srt_ParentCompanyMember_019e64ef-18a7-7be4-8630-a9600e717f6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7891-a06e-5e025f0648ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7891-a06e-5e025f0648ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7891-a06e-5e025f0648ff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7891-a06e-5e025f0648ff" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7891-a06e-5e025f0648ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7f01-af7c-1a76a9eb02ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e64ef-18a7-7891-a06e-5e025f0648ff" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7f01-af7c-1a76a9eb02ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ConvertibleNotesDueMaturingJune2027Member_019e64ef-18a7-721e-8d65-b32c5ecec192" xlink:href="pnw-20260630.xsd#pnw_ConvertibleNotesDueMaturingJune2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e64ef-18a7-7f01-af7c-1a76a9eb02ac" xlink:to="loc_pnw_ConvertibleNotesDueMaturingJune2027Member_019e64ef-18a7-721e-8d65-b32c5ecec192" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-18a7-7142-afa7-87ab32269fd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-18a7-7142-afa7-87ab32269fd8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-18a7-7142-afa7-87ab32269fd8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-18a7-7142-afa7-87ab32269fd8" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-18a7-7142-afa7-87ab32269fd8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-18a7-7941-b2d0-00912d866732" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e64ef-18a7-7142-afa7-87ab32269fd8" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-18a7-7941-b2d0-00912d866732" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_019e64ef-18a7-7ac5-ab99-9ec78edda651" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e64ef-18a7-7941-b2d0-00912d866732" xlink:to="loc_us-gaap_ConvertibleDebtMember_019e64ef-18a7-7ac5-ab99-9ec78edda651" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtInstrumentConvertibleTermsOfConversionAxis_019e64ef-18a7-7c6d-baa4-97fb3811aa56" xlink:href="pnw-20260630.xsd#pnw_DebtInstrumentConvertibleTermsOfConversionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-79bf-8962-e2bf65bf8938" xlink:to="loc_pnw_DebtInstrumentConvertibleTermsOfConversionAxis_019e64ef-18a7-7c6d-baa4-97fb3811aa56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtInstrumentConvertibleTermsOfConversionDomain_019e64ef-18a7-7c6d-baa4-97fb3811aa56_default" xlink:href="pnw-20260630.xsd#pnw_DebtInstrumentConvertibleTermsOfConversionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnw_DebtInstrumentConvertibleTermsOfConversionAxis_019e64ef-18a7-7c6d-baa4-97fb3811aa56" xlink:to="loc_pnw_DebtInstrumentConvertibleTermsOfConversionDomain_019e64ef-18a7-7c6d-baa4-97fb3811aa56_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtInstrumentConvertibleTermsOfConversionDomain_019e64ef-18a7-7b31-aaa8-bf1c5fa48bc9" xlink:href="pnw-20260630.xsd#pnw_DebtInstrumentConvertibleTermsOfConversionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnw_DebtInstrumentConvertibleTermsOfConversionAxis_019e64ef-18a7-7c6d-baa4-97fb3811aa56" xlink:to="loc_pnw_DebtInstrumentConvertibleTermsOfConversionDomain_019e64ef-18a7-7b31-aaa8-bf1c5fa48bc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtConversionTermsOneMember_019e64ef-18a7-7d99-b3cf-927723fe93e0" xlink:href="pnw-20260630.xsd#pnw_DebtConversionTermsOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DebtInstrumentConvertibleTermsOfConversionDomain_019e64ef-18a7-7b31-aaa8-bf1c5fa48bc9" xlink:to="loc_pnw_DebtConversionTermsOneMember_019e64ef-18a7-7d99-b3cf-927723fe93e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtConversionTermsTwoMember_019e64ef-18a7-75bc-824f-2095b48b11ec" xlink:href="pnw-20260630.xsd#pnw_DebtConversionTermsTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_DebtInstrumentConvertibleTermsOfConversionDomain_019e64ef-18a7-7b31-aaa8-bf1c5fa48bc9" xlink:to="loc_pnw_DebtConversionTermsTwoMember_019e64ef-18a7-75bc-824f-2095b48b11ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SaleOfStockOutstandingAgreementValueOfSharesToBeIssuedInTransaction_019e64ef-18a7-7a42-851f-48f199852eaf" xlink:href="pnw-20260630.xsd#pnw_SaleOfStockOutstandingAgreementValueOfSharesToBeIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_pnw_SaleOfStockOutstandingAgreementValueOfSharesToBeIssuedInTransaction_019e64ef-18a7-7a42-851f-48f199852eaf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SaleOfStockNumberOfForwardSaleAgreement_019e64ef-18a7-7456-875e-37f96f790238" xlink:href="pnw-20260630.xsd#pnw_SaleOfStockNumberOfForwardSaleAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_pnw_SaleOfStockNumberOfForwardSaleAgreement_019e64ef-18a7-7456-875e-37f96f790238" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ProceedsFromMarketOfferingsOfNetOfIssuanceCostsNotYetSettled_019e64ef-18a7-7609-bb04-a08f94c1256d" xlink:href="pnw-20260630.xsd#pnw_ProceedsFromMarketOfferingsOfNetOfIssuanceCostsNotYetSettled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_pnw_ProceedsFromMarketOfferingsOfNetOfIssuanceCostsNotYetSettled_019e64ef-18a7-7609-bb04-a08f94c1256d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019e64ef-18a7-7d10-9436-8fde608780ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019e64ef-18a7-7d10-9436-8fde608780ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e64ef-18a7-703a-ad7c-9a02fdf7ec05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e64ef-18a7-703a-ad7c-9a02fdf7ec05" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_019e64ef-18a7-7f51-a19e-e8f42525310f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_019e64ef-18a7-7f51-a19e-e8f42525310f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_019e64ef-18a7-7dc3-93a6-07d09a6fb34c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_019e64ef-18a7-7dc3-93a6-07d09a6fb34c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_019e64ef-18a7-738e-bbe3-11dceb5f19bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_019e64ef-18a7-738e-bbe3-11dceb5f19bd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_019e64ef-18a7-7ec4-96a5-a9fec6bbe4ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_019e64ef-18a7-7ec4-96a5-a9fec6bbe4ce" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_019e64ef-18a7-7ef2-8e87-63fd8dd916fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_019e64ef-18a7-7ef2-8e87-63fd8dd916fe" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019e64ef-18a7-7c96-ace6-2c21bb14fd1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019e64ef-18a7-7c96-ace6-2c21bb14fd1f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e64ef-18a7-77c0-bf55-ddbec2e90966" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e64ef-18a7-77c0-bf55-ddbec2e90966" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e64ef-18a7-75a8-9c3f-5ffe37640f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e64ef-18a7-75a8-9c3f-5ffe37640f3c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtFairValueDisclosures_019e64ef-18a7-734b-85df-590991f61913" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtFairValueDisclosures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7b92-afe6-2449c38260e1" xlink:to="loc_us-gaap_ConvertibleDebtFairValueDisclosures_019e64ef-18a7-734b-85df-590991f61913" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/CommonStockEquityandEarningsPerShareScheduleofATMProgramDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#CommonStockEquityandEarningsPerShareScheduleofATMProgramDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/CommonStockEquityandEarningsPerShareScheduleofATMProgramDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-78f0-bcfd-f6aa75916a37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-78f0-bcfd-f6aa75916a37" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-73af-98c4-c660799fd414" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-78f0-bcfd-f6aa75916a37" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-73af-98c4-c660799fd414" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-73af-98c4-c660799fd414_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-73af-98c4-c660799fd414" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-73af-98c4-c660799fd414_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-7952-8638-b497978d09c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019e64ef-18a7-73af-98c4-c660799fd414" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-7952-8638-b497978d09c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:href="pnw-20260630.xsd#pnw_ATMProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-7952-8638-b497978d09c6" xlink:to="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_November2024ATMForwardSaleAgreementMember_019e64ef-18a7-7800-a4ec-b1a1f5baf2b5" xlink:href="pnw-20260630.xsd#pnw_November2024ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_November2024ATMForwardSaleAgreementMember_019e64ef-18a7-7800-a4ec-b1a1f5baf2b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_March2025ATMForwardSaleAgreementMember_019e64ef-18a7-7a7b-9937-5b582dd1b9f4" xlink:href="pnw-20260630.xsd#pnw_March2025ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_March2025ATMForwardSaleAgreementMember_019e64ef-18a7-7a7b-9937-5b582dd1b9f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_August2025ATMForwardSaleAgreementMember_019e64ef-18a7-79e4-af63-389dadca756f" xlink:href="pnw-20260630.xsd#pnw_August2025ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_August2025ATMForwardSaleAgreementMember_019e64ef-18a7-79e4-af63-389dadca756f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_September2025ATMForwardSaleAgreementMember_019e64ef-18a7-7f2c-bbfa-958f39bcddd5" xlink:href="pnw-20260630.xsd#pnw_September2025ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_September2025ATMForwardSaleAgreementMember_019e64ef-18a7-7f2c-bbfa-958f39bcddd5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_January2026ATMForwardSaleAgreementMember_019e64ef-18a7-7cf2-b0d7-c7261b646207" xlink:href="pnw-20260630.xsd#pnw_January2026ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_January2026ATMForwardSaleAgreementMember_019e64ef-18a7-7cf2-b0d7-c7261b646207" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember32027Member_019e64ef-18a7-7774-950e-e24bc69a5f66" xlink:href="pnw-20260630.xsd#pnw_March2026ATMForwardSaleAgreementDueSeptember32027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember32027Member_019e64ef-18a7-7774-950e-e24bc69a5f66" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember102027Member_019e64ef-18a7-7b62-914c-37fb86a20eda" xlink:href="pnw-20260630.xsd#pnw_March2026ATMForwardSaleAgreementDueSeptember102027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember102027Member_019e64ef-18a7-7b62-914c-37fb86a20eda" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember182027Member_019e64ef-18a7-7e01-99b8-ca646c337f1b" xlink:href="pnw-20260630.xsd#pnw_March2026ATMForwardSaleAgreementDueSeptember182027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember182027Member_019e64ef-18a7-7e01-99b8-ca646c337f1b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember302027Member_019e64ef-18a7-75fe-a412-26599000a9fb" xlink:href="pnw-20260630.xsd#pnw_March2026ATMForwardSaleAgreementDueSeptember302027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_March2026ATMForwardSaleAgreementDueSeptember302027Member_019e64ef-18a7-75fe-a412-26599000a9fb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_April2026ATMForwardSaleAgreementMember_019f26d4-5501-7280-a70a-d70144c9f6aa" xlink:href="pnw-20260630.xsd#pnw_April2026ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_April2026ATMForwardSaleAgreementMember_019f26d4-5501-7280-a70a-d70144c9f6aa" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_May2026ATMForwardSaleAgreementMember_019f26d4-f4da-7307-a5d3-ee792f583b5e" xlink:href="pnw-20260630.xsd#pnw_May2026ATMForwardSaleAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_May2026ATMForwardSaleAgreementMember_019f26d4-f4da-7307-a5d3-ee792f583b5e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_June2026ATMForwardSaleAgreementDueDecember152027Member_019f26d5-64eb-70ff-9e37-3638d3979760" xlink:href="pnw-20260630.xsd#pnw_June2026ATMForwardSaleAgreementDueDecember152027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_June2026ATMForwardSaleAgreementDueDecember152027Member_019f26d5-64eb-70ff-9e37-3638d3979760" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_June2026ATMForwardSaleAgreementDueJune252028Member_019f26d6-15db-7f85-9785-a7dd7e4175e1" xlink:href="pnw-20260630.xsd#pnw_June2026ATMForwardSaleAgreementDueJune252028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_ATMProgramMember_019e64ef-18a7-7c2a-9be4-c24a4005f938" xlink:to="loc_pnw_June2026ATMForwardSaleAgreementDueJune252028Member_019f26d6-15db-7f85-9785-a7dd7e4175e1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_July2026ForwardSaleAgreementsMember_019f8d3e-2f97-761d-91cb-3c753e1409bf" xlink:href="pnw-20260630.xsd#pnw_July2026ForwardSaleAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-7952-8638-b497978d09c6" xlink:to="loc_pnw_July2026ForwardSaleAgreementsMember_019f8d3e-2f97-761d-91cb-3c753e1409bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_February2024ForwardSaleAgreementsMember_019f94d6-6e60-7d37-b0f3-2980a55e70ca" xlink:href="pnw-20260630.xsd#pnw_February2024ForwardSaleAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019e64ef-18a7-7952-8638-b497978d09c6" xlink:to="loc_pnw_February2024ForwardSaleAgreementsMember_019f94d6-6e60-7d37-b0f3-2980a55e70ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f8d3f-01ad-7db1-aaa7-5555022af88a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSubsidiaryOrEquityMethodInvesteeTable_019e64ef-18a7-78f0-bcfd-f6aa75916a37" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f8d3f-01ad-7db1-aaa7-5555022af88a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f8d3f-01ad-7db1-aaa7-5555022af88a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f8d3f-01ad-7db1-aaa7-5555022af88a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f8d3f-01ad-7db1-aaa7-5555022af88a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f8d3f-01ad-752f-80a9-674276dc47d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019f8d3f-01ad-7db1-aaa7-5555022af88a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f8d3f-01ad-752f-80a9-674276dc47d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f8d3f-19f1-7741-8d77-4124e9a51c07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019f8d3f-01ad-752f-80a9-674276dc47d6" xlink:to="loc_us-gaap_SubsequentEventMember_019f8d3f-19f1-7741-8d77-4124e9a51c07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SaleOfStockExpectedNumberOfSharesToBeIssuedInTransaction_019e64ef-18a7-7921-a3bf-f3a81da8d1c8" xlink:href="pnw-20260630.xsd#pnw_SaleOfStockExpectedNumberOfSharesToBeIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_pnw_SaleOfStockExpectedNumberOfSharesToBeIssuedInTransaction_019e64ef-18a7-7921-a3bf-f3a81da8d1c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SaleOfStockOutstandingAgreementValueOfSharesToBeIssuedInTransaction_019e64ef-18a7-7761-a13e-db1c14946e42" xlink:href="pnw-20260630.xsd#pnw_SaleOfStockOutstandingAgreementValueOfSharesToBeIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_pnw_SaleOfStockOutstandingAgreementValueOfSharesToBeIssuedInTransaction_019e64ef-18a7-7761-a13e-db1c14946e42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_019e64ef-18a7-7ee2-8c12-d67f445dde12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_019e64ef-18a7-7ee2-8c12-d67f445dde12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_019e64ef-18a7-72b9-bb8d-631051766664" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_019e64ef-18a7-72b9-bb8d-631051766664" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SaleOfStockNumberOfForwardSaleAgreement_019fa19b-818d-74c4-819a-07ed91cfa329" xlink:href="pnw-20260630.xsd#pnw_SaleOfStockNumberOfForwardSaleAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_pnw_SaleOfStockNumberOfForwardSaleAgreement_019fa19b-818d-74c4-819a-07ed91cfa329" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_019e64ef-18a7-788f-b42e-501a9075e027" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeLineItems_019e64ef-18a7-7f5e-9453-18fcf4e9cb71" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_019e64ef-18a7-788f-b42e-501a9075e027" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/CommonStockEquityandEarningsPerShareScheduleofEarningsPerShareBasicandDilutedDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#CommonStockEquityandEarningsPerShareScheduleofEarningsPerShareBasicandDilutedDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/CommonStockEquityandEarningsPerShareScheduleofEarningsPerShareBasicandDilutedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasicLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_019e64ef-18a7-76ef-b3f0-99205285874c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_019e64ef-18a7-76ef-b3f0-99205285874c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e64ef-18a7-7caa-bcdb-c9192d35f17e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_019e64ef-18a7-76ef-b3f0-99205285874c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e64ef-18a7-7caa-bcdb-c9192d35f17e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e64ef-18a7-7caa-bcdb-c9192d35f17e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e64ef-18a7-7caa-bcdb-c9192d35f17e" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e64ef-18a7-7caa-bcdb-c9192d35f17e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e64ef-18a7-79fd-8db0-f01864637b21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e64ef-18a7-7caa-bcdb-c9192d35f17e" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e64ef-18a7-79fd-8db0-f01864637b21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ATMProgramMember_019e64ef-18a7-7007-bb92-6ea4e54095dc" xlink:href="pnw-20260630.xsd#pnw_ATMProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e64ef-18a7-79fd-8db0-f01864637b21" xlink:to="loc_pnw_ATMProgramMember_019e64ef-18a7-7007-bb92-6ea4e54095dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleNotesPayableMember_019e64ef-18a7-7627-a80a-15c637a0e84b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleNotesPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e64ef-18a7-79fd-8db0-f01864637b21" xlink:to="loc_us-gaap_ConvertibleNotesPayableMember_019e64ef-18a7-7627-a80a-15c637a0e84b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e64ef-18a7-7cc9-9215-ddd3c5f0f358" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e64ef-18a7-7cc9-9215-ddd3c5f0f358" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_019fb8b3-5ee9-76ee-bbc8-857aeac7d031" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_019fb8b3-5ee9-76ee-bbc8-857aeac7d031" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e64ef-18a7-7851-936d-a7a862a1bd0c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e64ef-18a7-7851-936d-a7a862a1bd0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e64ef-18a7-7717-9f91-b3c19d49deec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e64ef-18a7-7717-9f91-b3c19d49deec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e64ef-18a7-7ddc-a96f-74dd8d64e796" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e64ef-18a7-7717-9f91-b3c19d49deec" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e64ef-18a7-7ddc-a96f-74dd8d64e796" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToEquityForwardAgreements_019e64ef-18a7-75d8-95d3-c71fe5dbc3be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToEquityForwardAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e64ef-18a7-7717-9f91-b3c19d49deec" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToEquityForwardAgreements_019e64ef-18a7-75d8-95d3-c71fe5dbc3be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities_019e64ef-18a7-79a0-8346-ba83bb2305ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e64ef-18a7-7717-9f91-b3c19d49deec" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities_019e64ef-18a7-79a0-8346-ba83bb2305ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToContingentlyIssuableShares_019e64ef-18a7-7426-9fe9-210048c63002" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToContingentlyIssuableShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e64ef-18a7-7717-9f91-b3c19d49deec" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToContingentlyIssuableShares_019e64ef-18a7-7426-9fe9-210048c63002" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_WeightedAverageNumberOfSharesOutstandingDilutedAndContingentlyIssuableShares_019e64ef-18a7-7bf3-a689-f965cf77be99" xlink:href="pnw-20260630.xsd#pnw_WeightedAverageNumberOfSharesOutstandingDilutedAndContingentlyIssuableShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_pnw_WeightedAverageNumberOfSharesOutstandingDilutedAndContingentlyIssuableShares_019e64ef-18a7-7bf3-a689-f965cf77be99" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019e64ef-18a7-74ed-9509-e582b240b163" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019e64ef-18a7-74ed-9509-e582b240b163" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e64ef-18a7-7126-9e42-d56dde56e7ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019e64ef-18a7-74ed-9509-e582b240b163" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e64ef-18a7-7126-9e42-d56dde56e7ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e64ef-18a7-7792-a97c-2b44e3addce0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019e64ef-18a7-74ed-9509-e582b240b163" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e64ef-18a7-7792-a97c-2b44e3addce0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e64ef-18a7-79e1-993c-3b47a18a9a70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_019e64ef-18a7-75c6-aec5-4144b65183bc" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e64ef-18a7-79e1-993c-3b47a18a9a70" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/FairValueMeasurementsScheduleofAssetsandLiabilitiesMeasuredonaRecurringBasisDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#FairValueMeasurementsScheduleofAssetsandLiabilitiesMeasuredonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/FairValueMeasurementsScheduleofAssetsandLiabilitiesMeasuredonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e64ef-18a7-7960-a05c-05292166564e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e64ef-18a7-79e7-b362-531ac64a3285" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e64ef-18a7-7960-a05c-05292166564e" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e64ef-18a7-79e7-b362-531ac64a3285" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7ca1-a2cb-a03e859b6f60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e64ef-18a7-79e7-b362-531ac64a3285" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7ca1-a2cb-a03e859b6f60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7ca1-a2cb-a03e859b6f60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7ca1-a2cb-a03e859b6f60" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7ca1-a2cb-a03e859b6f60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7172-a6de-9412665eb7fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7ca1-a2cb-a03e859b6f60" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7172-a6de-9412665eb7fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e64ef-18a7-737c-aaeb-632de2383866" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7172-a6de-9412665eb7fa" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e64ef-18a7-737c-aaeb-632de2383866" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e64ef-18a7-768f-8856-6e3bb87c5eba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7172-a6de-9412665eb7fa" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e64ef-18a7-768f-8856-6e3bb87c5eba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e64ef-18a7-751e-9f4e-f36c53df1adf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7172-a6de-9412665eb7fa" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e64ef-18a7-751e-9f4e-f36c53df1adf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019e64ef-18a7-7500-a0ea-1fef78db57c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7172-a6de-9412665eb7fa" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019e64ef-18a7-7500-a0ea-1fef78db57c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7efe-aa55-ec785d25d3f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e64ef-18a7-79e7-b362-531ac64a3285" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7efe-aa55-ec785d25d3f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7efe-aa55-ec785d25d3f6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7efe-aa55-ec785d25d3f6" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7efe-aa55-ec785d25d3f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7efe-aa55-ec785d25d3f6" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_019e64ef-18a7-78b2-8572-3a8b3fc9fef4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_us-gaap_EquitySecuritiesMember_019e64ef-18a7-78b2-8572-3a8b3fc9fef4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_USCommingledFundsMember_019e64ef-18a7-7fb2-98df-240aa8a9f8db" xlink:href="pnw-20260630.xsd#pnw_USCommingledFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_pnw_USCommingledFundsMember_019e64ef-18a7-7fb2-98df-240aa8a9f8db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_019e64ef-18a7-7ce3-bb07-38006d71aae1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_019e64ef-18a7-7ce3-bb07-38006d71aae1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019e64ef-18a7-7e24-a1b2-364137b835a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019e64ef-18a7-7e24-a1b2-364137b835a4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_019e64ef-18a7-7aeb-9ef7-313791bd3833" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_019e64ef-18a7-7aeb-9ef7-313791bd3833" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_019e64ef-18a7-7b89-9a93-fef9b96f6777" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_019e64ef-18a7-7b89-9a93-fef9b96f6777" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDebtSecuritiesMember_019e64ef-18a7-78ff-ae68-7b30b8e60e34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_us-gaap_OtherDebtSecuritiesMember_019e64ef-18a7-78ff-ae68-7b30b8e60e34" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OtherEquitySecuritiesMember_019f8323-608b-76d0-b16c-69ef43528e58" xlink:href="pnw-20260630.xsd#pnw_OtherEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-709f-a871-6a6ba207b0f1" xlink:to="loc_pnw_OtherEquitySecuritiesMember_019f8323-608b-76d0-b16c-69ef43528e58" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-7cc2-890b-3406a088c03b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e64ef-18a7-79e7-b362-531ac64a3285" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-7cc2-890b-3406a088c03b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7cc2-890b-3406a088c03b_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7cc2-890b-3406a088c03b" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7cc2-890b-3406a088c03b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-71d0-b972-e752698e66a9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7cc2-890b-3406a088c03b" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-71d0-b972-e752698e66a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PinnacleWestCaptiveInsuranceCellMember_019e64ef-18a7-7fda-b4cc-e3ee2b683e99" xlink:href="pnw-20260630.xsd#pnw_PinnacleWestCaptiveInsuranceCellMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-71d0-b972-e752698e66a9" xlink:to="loc_pnw_PinnacleWestCaptiveInsuranceCellMember_019e64ef-18a7-7fda-b4cc-e3ee2b683e99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7d6e-b464-65e60d8a3cd4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e64ef-18a7-79e7-b362-531ac64a3285" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7d6e-b464-65e60d8a3cd4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d6e-b464-65e60d8a3cd4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7d6e-b464-65e60d8a3cd4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7d6e-b464-65e60d8a3cd4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-70d0-84e6-d8f81e055397" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7d6e-b464-65e60d8a3cd4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-70d0-84e6-d8f81e055397" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityOptionMember_019e64ef-18a7-7be7-9191-5f336082c548" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-70d0-84e6-d8f81e055397" xlink:to="loc_us-gaap_CommodityOptionMember_019e64ef-18a7-7be7-9191-5f336082c548" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e64ef-18a7-7960-a05c-05292166564e" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019f831a-b56b-746d-a73f-c40728e0f0f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019f831a-b56b-746d-a73f-c40728e0f0f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e64ef-18a7-7ae7-a47b-44fcb247d970" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e64ef-18a7-7ae7-a47b-44fcb247d970" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e64ef-18a7-7714-9a00-b48131a97c8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e64ef-18a7-7714-9a00-b48131a97c8d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e64ef-18a7-7293-b19a-727ba2cc83a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_us-gaap_DerivativeAssets_019e64ef-18a7-7293-b19a-727ba2cc83a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_019e64ef-18a7-7857-abd1-d236b5450537" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_019e64ef-18a7-7857-abd1-d236b5450537" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DecommissioningFundInvestmentsFairValueNetPendingSecuritiesSalesAndPurchases_019e64ef-18a7-79f7-8d6d-38ad5f673e0f" xlink:href="pnw-20260630.xsd#pnw_DecommissioningFundInvestmentsFairValueNetPendingSecuritiesSalesAndPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_pnw_DecommissioningFundInvestmentsFairValueNetPendingSecuritiesSalesAndPurchases_019e64ef-18a7-79f7-8d6d-38ad5f673e0f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SpecialUseFundInvestmentsOtherGrossFairValue_019e64ef-18a7-7d69-b576-bc5d7ba65e5a" xlink:href="pnw-20260630.xsd#pnw_SpecialUseFundInvestmentsOtherGrossFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_pnw_SpecialUseFundInvestmentsOtherGrossFairValue_019e64ef-18a7-7d69-b576-bc5d7ba65e5a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SpecialUseFundInvestmentsOtherNetFairValuePendingSalesAndPurchases_019e64ef-18a7-73bd-9b56-31320df06a42" xlink:href="pnw-20260630.xsd#pnw_SpecialUseFundInvestmentsOtherNetFairValuePendingSalesAndPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_pnw_SpecialUseFundInvestmentsOtherNetFairValuePendingSalesAndPurchases_019e64ef-18a7-73bd-9b56-31320df06a42" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019e64ef-18a7-7ad4-ae11-5f024496ef0c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019e64ef-18a7-7ad4-ae11-5f024496ef0c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_AssetsFairValueGrossLiabilityAndNetPendingSecuritiesSalesAndPurchases_019e64ef-18a7-7e98-97d6-a730cc3a5bc3" xlink:href="pnw-20260630.xsd#pnw_AssetsFairValueGrossLiabilityAndNetPendingSecuritiesSalesAndPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e64ef-18a7-7bf6-a0c3-a37ad583775b" xlink:to="loc_pnw_AssetsFairValueGrossLiabilityAndNetPendingSecuritiesSalesAndPurchases_019e64ef-18a7-7e98-97d6-a730cc3a5bc3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e64ef-18a7-71af-acd0-a0f83bfdf5d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e64ef-18a7-7960-a05c-05292166564e" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e64ef-18a7-71af-acd0-a0f83bfdf5d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e64ef-18a7-780d-8512-06be317933d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e64ef-18a7-71af-acd0-a0f83bfdf5d9" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e64ef-18a7-780d-8512-06be317933d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e64ef-18a7-7342-85dd-d268ff62dae8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e64ef-18a7-71af-acd0-a0f83bfdf5d9" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e64ef-18a7-7342-85dd-d268ff62dae8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-7d4a-8ca1-f7be4012dafc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e64ef-18a7-71af-acd0-a0f83bfdf5d9" xlink:to="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-7d4a-8ca1-f7be4012dafc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/FairValueMeasurementsScheduleofSignificantUnobservableInputsUsedtoValueLevel3InstrumentsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#FairValueMeasurementsScheduleofSignificantUnobservableInputsUsedtoValueLevel3InstrumentsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/FairValueMeasurementsScheduleofSignificantUnobservableInputsUsedtoValueLevel3InstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_019e64ef-18a7-7111-b954-9fe75d5354da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_019e64ef-18a7-7306-800e-185b21affa5d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_019e64ef-18a7-7111-b954-9fe75d5354da" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_019e64ef-18a7-7306-800e-185b21affa5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7ef5-b8af-fc80a0ce6b15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_019e64ef-18a7-7306-800e-185b21affa5d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7ef5-b8af-fc80a0ce6b15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7ef5-b8af-fc80a0ce6b15_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7ef5-b8af-fc80a0ce6b15" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7ef5-b8af-fc80a0ce6b15_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-72cc-8a11-cc2b6ac25238" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-7ef5-b8af-fc80a0ce6b15" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-72cc-8a11-cc2b6ac25238" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7b99-9fe4-4ae5fc25e011" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-72cc-8a11-cc2b6ac25238" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7b99-9fe4-4ae5fc25e011" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ElectricityForwardContractMember_019e64ef-18a7-7f91-af44-db4d8d92f565" xlink:href="pnw-20260630.xsd#pnw_ElectricityForwardContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7b99-9fe4-4ae5fc25e011" xlink:to="loc_pnw_ElectricityForwardContractMember_019e64ef-18a7-7f91-af44-db4d8d92f565" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NaturalGasForwardContractMember_019e64ef-18a7-790f-a4cc-e6fb7b62f304" xlink:href="pnw-20260630.xsd#pnw_NaturalGasForwardContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7b99-9fe4-4ae5fc25e011" xlink:to="loc_pnw_NaturalGasForwardContractMember_019e64ef-18a7-790f-a4cc-e6fb7b62f304" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e64ef-18a7-7ac2-9f61-47f72dda3007" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_019e64ef-18a7-7306-800e-185b21affa5d" xlink:to="loc_srt_RangeAxis_019e64ef-18a7-7ac2-9f61-47f72dda3007" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e64ef-18a7-7ac2-9f61-47f72dda3007_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e64ef-18a7-7ac2-9f61-47f72dda3007" xlink:to="loc_srt_RangeMember_019e64ef-18a7-7ac2-9f61-47f72dda3007_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e64ef-18a7-7043-8045-71a78a7877bb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e64ef-18a7-7ac2-9f61-47f72dda3007" xlink:to="loc_srt_RangeMember_019e64ef-18a7-7043-8045-71a78a7877bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e64ef-18a7-768f-bd68-7b99b1fb5c0e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e64ef-18a7-7043-8045-71a78a7877bb" xlink:to="loc_srt_MinimumMember_019e64ef-18a7-768f-bd68-7b99b1fb5c0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e64ef-18a7-73b8-ba7e-4833ac96ef58" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e64ef-18a7-7043-8045-71a78a7877bb" xlink:to="loc_srt_MaximumMember_019e64ef-18a7-73b8-ba7e-4833ac96ef58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_019e64ef-18a7-7c4f-a30c-17d7d65e4c61" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e64ef-18a7-7043-8045-71a78a7877bb" xlink:to="loc_srt_WeightedAverageMember_019e64ef-18a7-7c4f-a30c-17d7d65e4c61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7f1a-8f9e-86c75893dc27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_019e64ef-18a7-7306-800e-185b21affa5d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7f1a-8f9e-86c75893dc27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7f1a-8f9e-86c75893dc27_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7f1a-8f9e-86c75893dc27" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7f1a-8f9e-86c75893dc27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-75d4-b998-b3bb3b6ee159" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-7f1a-8f9e-86c75893dc27" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-75d4-b998-b3bb3b6ee159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e64ef-18a7-799d-bd73-62a66301630c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-75d4-b998-b3bb3b6ee159" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e64ef-18a7-799d-bd73-62a66301630c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e64ef-18a7-728d-98e4-26ca260927f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_019e64ef-18a7-7111-b954-9fe75d5354da" xlink:to="loc_us-gaap_DerivativeAssets_019e64ef-18a7-728d-98e4-26ca260927f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-7e1e-8900-67da4a5ef3c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_019e64ef-18a7-7111-b954-9fe75d5354da" xlink:to="loc_us-gaap_DerivativeLiabilities_019e64ef-18a7-7e1e-8900-67da4a5ef3c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityMeasurementInput_019e64ef-18a7-7e02-a1a1-9c7a55700174" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_019e64ef-18a7-7111-b954-9fe75d5354da" xlink:to="loc_us-gaap_DerivativeLiabilityMeasurementInput_019e64ef-18a7-7e02-a1a1-9c7a55700174" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetMeasurementInput_019e64ef-18a7-7cad-a3c8-92285cb1c02a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_019e64ef-18a7-7111-b954-9fe75d5354da" xlink:to="loc_us-gaap_DerivativeAssetMeasurementInput_019e64ef-18a7-7cad-a3c8-92285cb1c02a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/FairValueMeasurementsScheduleofFairValueforOurRiskManagementActivitiesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#FairValueMeasurementsScheduleofFairValueforOurRiskManagementActivitiesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/FairValueMeasurementsScheduleofFairValueforOurRiskManagementActivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e64ef-18a7-7f88-85a3-ecc7908a883f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e64ef-18a7-7886-97e1-d0f78d4d7b43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e64ef-18a7-7f88-85a3-ecc7908a883f" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e64ef-18a7-7886-97e1-d0f78d4d7b43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-74ce-b24c-2253ad63d818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e64ef-18a7-7886-97e1-d0f78d4d7b43" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-74ce-b24c-2253ad63d818" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-74ce-b24c-2253ad63d818_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-74ce-b24c-2253ad63d818" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-74ce-b24c-2253ad63d818_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7503-ba9c-ca16759306fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e64ef-18a7-74ce-b24c-2253ad63d818" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7503-ba9c-ca16759306fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7374-ab2c-068380717d7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e64ef-18a7-7503-ba9c-ca16759306fd" xlink:to="loc_us-gaap_CommodityContractMember_019e64ef-18a7-7374-ab2c-068380717d7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-78dd-a9fb-6df62830ce90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e64ef-18a7-7886-97e1-d0f78d4d7b43" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-78dd-a9fb-6df62830ce90" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-78dd-a9fb-6df62830ce90_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-78dd-a9fb-6df62830ce90" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-78dd-a9fb-6df62830ce90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7e9f-9376-f2a788af6cce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e64ef-18a7-78dd-a9fb-6df62830ce90" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7e9f-9376-f2a788af6cce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e64ef-18a7-71af-af39-5b64d85d72a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e64ef-18a7-7e9f-9376-f2a788af6cce" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e64ef-18a7-71af-af39-5b64d85d72a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e64ef-18a7-7f88-85a3-ecc7908a883f" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_019e64ef-18a7-760b-9ef8-80fbd90226e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_019e64ef-18a7-760b-9ef8-80fbd90226e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRegulatoryAssetsAndLiabilities_019e64ef-18a7-7c6c-a36f-a52dc446a06c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInRegulatoryAssetsAndLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:to="loc_us-gaap_IncreaseDecreaseInRegulatoryAssetsAndLiabilities_019e64ef-18a7-7c6c-a36f-a52dc446a06c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_019e64ef-18a7-700a-bd1a-f5d5816b6a94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_019e64ef-18a7-700a-bd1a-f5d5816b6a94" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3_019e64ef-18a7-7993-a34d-5ac47a67dad1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3_019e64ef-18a7-7993-a34d-5ac47a67dad1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e64ef-18a7-7ce4-a37e-0d217f541003" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_019e64ef-18a7-7be7-b887-84b94febf389" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e64ef-18a7-7ce4-a37e-0d217f541003" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_019e64ef-18a7-7185-889e-355a5db0f4f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityRecurringBasisStillHeldUnrealizedGainLossOci_019e64ef-18a7-7f50-9e2d-c5904d60636d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityRecurringBasisStillHeldUnrealizedGainLossOci"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e64ef-18a7-7f88-85a3-ecc7908a883f" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityRecurringBasisStillHeldUnrealizedGainLossOci_019e64ef-18a7-7f50-9e2d-c5904d60636d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/InvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#InvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/InvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7b25-b0a0-977ddd74f852" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-7608-8108-e61db8e203ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7b25-b0a0-977ddd74f852" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-7608-8108-e61db8e203ef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-79ec-aa98-70edfdd20e9a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-7608-8108-e61db8e203ef" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-79ec-aa98-70edfdd20e9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-79ec-aa98-70edfdd20e9a_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-79ec-aa98-70edfdd20e9a" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-79ec-aa98-70edfdd20e9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7421-9cf6-65ba8d8091db" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-79ec-aa98-70edfdd20e9a" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7421-9cf6-65ba8d8091db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7af2-be79-94a655772a5c" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-7421-9cf6-65ba8d8091db" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7af2-be79-94a655772a5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_EmployeeMedicalClaimsAmount_019e64ef-18a7-7d36-914d-9116d2cf24d0" xlink:href="pnw-20260630.xsd#pnw_EmployeeMedicalClaimsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7b25-b0a0-977ddd74f852" xlink:to="loc_pnw_EmployeeMedicalClaimsAmount_019e64ef-18a7-7d36-914d-9116d2cf24d0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/InvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsScheduleofInvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#InvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsScheduleofInvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/InvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsScheduleofInvestmentsinNuclearDecommissioningTrustsandOtherSpecialUseFundsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-7143-86fe-aff74c4ba3b6" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-7143-86fe-aff74c4ba3b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7143-86fe-aff74c4ba3b6_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7143-86fe-aff74c4ba3b6" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7143-86fe-aff74c4ba3b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-73a3-bfb5-f3c9a9cea0c1" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-7143-86fe-aff74c4ba3b6" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-73a3-bfb5-f3c9a9cea0c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-75fc-b52f-574ef9b27297" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-73a3-bfb5-f3c9a9cea0c1" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-75fc-b52f-574ef9b27297" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7c24-8488-1e3c9d364e60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7c24-8488-1e3c9d364e60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7c24-8488-1e3c9d364e60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7c24-8488-1e3c9d364e60" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7c24-8488-1e3c9d364e60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7371-8c88-8ce5e8db4671" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e64ef-18a7-7c24-8488-1e3c9d364e60" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7371-8c88-8ce5e8db4671" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_019e64ef-18a7-71d7-b0eb-2c3db6046657" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7371-8c88-8ce5e8db4671" xlink:to="loc_us-gaap_EquitySecuritiesMember_019e64ef-18a7-71d7-b0eb-2c3db6046657" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedIncomeSecuritiesMember_019e64ef-18a7-7849-aebb-ea8d7ef65c38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FixedIncomeSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7371-8c88-8ce5e8db4671" xlink:to="loc_us-gaap_FixedIncomeSecuritiesMember_019e64ef-18a7-7849-aebb-ea8d7ef65c38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OtherReceivablesfromBrokerDealersandClearingMember_019e64ef-18a7-7320-9d4e-023df0db0a96" xlink:href="pnw-20260630.xsd#pnw_OtherReceivablesfromBrokerDealersandClearingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e64ef-18a7-7371-8c88-8ce5e8db4671" xlink:to="loc_pnw_OtherReceivablesfromBrokerDealersandClearingMember_019e64ef-18a7-7320-9d4e-023df0db0a96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_InvestmentsTypeAxis_019e64ef-18a7-7a70-a551-d0bb4707570f" xlink:href="pnw-20260630.xsd#pnw_InvestmentsTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:to="loc_pnw_InvestmentsTypeAxis_019e64ef-18a7-7a70-a551-d0bb4707570f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7a70-a551-d0bb4707570f_default" xlink:href="pnw-20260630.xsd#pnw_InvestmentsTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnw_InvestmentsTypeAxis_019e64ef-18a7-7a70-a551-d0bb4707570f" xlink:to="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7a70-a551-d0bb4707570f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:href="pnw-20260630.xsd#pnw_InvestmentsTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnw_InvestmentsTypeAxis_019e64ef-18a7-7a70-a551-d0bb4707570f" xlink:to="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NuclearDecommissioningTrustsMember_019e64ef-18a7-7ee5-97d7-4921ceb36608" xlink:href="pnw-20260630.xsd#pnw_NuclearDecommissioningTrustsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:to="loc_pnw_NuclearDecommissioningTrustsMember_019e64ef-18a7-7ee5-97d7-4921ceb36608" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_OtherSpecialUseFundsMember_019e64ef-18a7-7ee7-90a1-20bd290391b2" xlink:href="pnw-20260630.xsd#pnw_OtherSpecialUseFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:to="loc_pnw_OtherSpecialUseFundsMember_019e64ef-18a7-7ee7-90a1-20bd290391b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CoalReclamationEscrowAccountsMember_019e64ef-18a7-75fe-9980-7aff9f8b1700" xlink:href="pnw-20260630.xsd#pnw_CoalReclamationEscrowAccountsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:to="loc_pnw_CoalReclamationEscrowAccountsMember_019e64ef-18a7-75fe-9980-7aff9f8b1700" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ActiveUnionMedicalTrustMember_019e64ef-18a7-7cef-a8ef-d011a1182ad9" xlink:href="pnw-20260630.xsd#pnw_ActiveUnionMedicalTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:to="loc_pnw_ActiveUnionMedicalTrustMember_019e64ef-18a7-7cef-a8ef-d011a1182ad9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CapitveInsuranceCellMember_019e64ef-18a7-708b-a48f-9d5c11696baf" xlink:href="pnw-20260630.xsd#pnw_CapitveInsuranceCellMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_InvestmentsTypeDomain_019e64ef-18a7-7358-964c-dcab82c8065e" xlink:to="loc_pnw_CapitveInsuranceCellMember_019e64ef-18a7-708b-a48f-9d5c11696baf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7aec-9ee2-4d38ace33267" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7aec-9ee2-4d38ace33267" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7aec-9ee2-4d38ace33267_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7aec-9ee2-4d38ace33267" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7aec-9ee2-4d38ace33267_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-71c6-96de-7a33032860cd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7aec-9ee2-4d38ace33267" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-71c6-96de-7a33032860cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-736a-81fa-55a09032157b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-71c6-96de-7a33032860cd" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-736a-81fa-55a09032157b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-71cb-9162-337fa97fc5d4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e64ef-18a7-76f0-903b-c009b67483b0" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-71cb-9162-337fa97fc5d4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-71cb-9162-337fa97fc5d4_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-71cb-9162-337fa97fc5d4" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-71cb-9162-337fa97fc5d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-76eb-95e6-4e18a2c4cd27" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-71cb-9162-337fa97fc5d4" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-76eb-95e6-4e18a2c4cd27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PinnacleWestCaptiveInsuranceCellMember_019e64ef-18a7-73b8-85d4-02b8fdf07c58" xlink:href="pnw-20260630.xsd#pnw_PinnacleWestCaptiveInsuranceCellMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-76eb-95e6-4e18a2c4cd27" xlink:to="loc_pnw_PinnacleWestCaptiveInsuranceCellMember_019e64ef-18a7-73b8-85d4-02b8fdf07c58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_019e64ef-18a7-7b18-a00a-492b80115e31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_019e64ef-18a7-7b18-a00a-492b80115e31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGain_019e64ef-18a7-76c7-8493-af33c4d9db89" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGain_019e64ef-18a7-76c7-8493-af33c4d9db89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedLoss_019e64ef-18a7-7874-9894-a508f6786f35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedLoss_019e64ef-18a7-7874-9894-a508f6786f35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019e64ef-18a7-7e04-bfce-bd647aa80075" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019e64ef-18a7-7e04-bfce-bd647aa80075" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain_019e64ef-18a7-7370-9edf-d9603d714517" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain_019e64ef-18a7-7370-9edf-d9603d714517" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_019e64ef-18a7-7a5a-b98a-388aed16c9b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_019e64ef-18a7-7a5a-b98a-388aed16c9b8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtSecuritiesAvailableForSaleOther_019e64ef-18a7-706b-ae7a-1662c9756b0a" xlink:href="pnw-20260630.xsd#pnw_DebtSecuritiesAvailableForSaleOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_pnw_DebtSecuritiesAvailableForSaleOther_019e64ef-18a7-706b-ae7a-1662c9756b0a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtSecuritiesAvailableForSaleOtherUnrealizedGain_019e64ef-18a7-70b6-afaa-76cb6b04ef63" xlink:href="pnw-20260630.xsd#pnw_DebtSecuritiesAvailableForSaleOtherUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_pnw_DebtSecuritiesAvailableForSaleOtherUnrealizedGain_019e64ef-18a7-70b6-afaa-76cb6b04ef63" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtSecuritiesAvailableForSaleOtherUnrealizedLoss_019e64ef-18a7-7e84-b358-31f5cdc851e1" xlink:href="pnw-20260630.xsd#pnw_DebtSecuritiesAvailableForSaleOtherUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_pnw_DebtSecuritiesAvailableForSaleOtherUnrealizedLoss_019e64ef-18a7-7e84-b358-31f5cdc851e1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Investments_019e64ef-18a7-72f8-81bf-376584682662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Investments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_Investments_019e64ef-18a7-72f8-81bf-376584682662" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtAndEquitySecuritiesUnrealizedGain_019e64ef-18a7-7656-b1ad-ec16045045e2" xlink:href="pnw-20260630.xsd#pnw_DebtAndEquitySecuritiesUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_pnw_DebtAndEquitySecuritiesUnrealizedGain_019e64ef-18a7-7656-b1ad-ec16045045e2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DebtAndEquitySecuritiesUnrealizedLoss_019e64ef-18a7-75ec-8bf4-1fa9e73e3fdc" xlink:href="pnw-20260630.xsd#pnw_DebtAndEquitySecuritiesUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_pnw_DebtAndEquitySecuritiesUnrealizedLoss_019e64ef-18a7-75ec-8bf4-1fa9e73e3fdc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019e64ef-18a7-7b6b-a2ec-2db6693fb872" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019e64ef-18a7-7b6b-a2ec-2db6693fb872" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_019e64ef-18a7-759a-b90d-26c52516877c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_019e64ef-18a7-759a-b90d-26c52516877c" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract_019e64ef-18a7-725f-956b-6d52e2bbf5ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract_019e64ef-18a7-725f-956b-6d52e2bbf5ad" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGain_019e64ef-18a7-7c2b-a83d-3894d5799ffb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract_019e64ef-18a7-725f-956b-6d52e2bbf5ad" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGain_019e64ef-18a7-7c2b-a83d-3894d5799ffb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019e64ef-18a7-70b8-8dc5-292de0b0d795" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract_019e64ef-18a7-725f-956b-6d52e2bbf5ad" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019e64ef-18a7-70b8-8dc5-292de0b0d795" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019e64ef-18a7-7442-aabb-409f1f75b890" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract_019e64ef-18a7-725f-956b-6d52e2bbf5ad" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019e64ef-18a7-7442-aabb-409f1f75b890" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e64ef-18a7-79a6-979f-af1f0ba725be" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_019e64ef-18a7-7f3d-8f7c-c71730ddf8e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_019e64ef-18a7-7f3d-8f7c-c71730ddf8e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_019e64ef-18a7-76ba-8d2a-85fb2e8cf5c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_019e64ef-18a7-76ba-8d2a-85fb2e8cf5c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_019e64ef-18a7-7715-be30-931169dc0e95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_019e64ef-18a7-7715-be30-931169dc0e95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_019e64ef-18a7-7cb8-909f-5302582dd1af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_019e64ef-18a7-7cb8-909f-5302582dd1af" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_DecommissioningAndOtherSpecialUseFundInvestmentsFairValue_019e64ef-18a7-7be7-b1e3-3a3f13f7951e" xlink:href="pnw-20260630.xsd#pnw_DecommissioningAndOtherSpecialUseFundInvestmentsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueAbstract_019e64ef-18a7-7734-8f0c-76ad5d4c0815" xlink:to="loc_pnw_DecommissioningAndOtherSpecialUseFundInvestmentsFairValue_019e64ef-18a7-7be7-b1e3-3a3f13f7951e" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ChangesinAccumulatedOtherComprehensiveLossDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#ChangesinAccumulatedOtherComprehensiveLossDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ChangesinAccumulatedOtherComprehensiveLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e64ef-18a7-7441-b881-81b799d2e6df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e64ef-18a7-7cce-8c02-bdca6c469e28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e64ef-18a7-7441-b881-81b799d2e6df" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e64ef-18a7-7cce-8c02-bdca6c469e28" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-75c6-928d-47acec72d29d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e64ef-18a7-7cce-8c02-bdca6c469e28" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-75c6-928d-47acec72d29d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-75c6-928d-47acec72d29d_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-75c6-928d-47acec72d29d" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-75c6-928d-47acec72d29d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-7238-b6b0-3d092efbe4ee" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-75c6-928d-47acec72d29d" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-7238-b6b0-3d092efbe4ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7c0f-905b-7652ddcdcfd7" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-7238-b6b0-3d092efbe4ee" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7c0f-905b-7652ddcdcfd7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-18a7-7e71-941b-ebbf14137eee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e64ef-18a7-7cce-8c02-bdca6c469e28" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-18a7-7e71-941b-ebbf14137eee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e64ef-18a7-7e71-941b-ebbf14137eee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-18a7-7e71-941b-ebbf14137eee" xlink:to="loc_us-gaap_EquityComponentDomain_019e64ef-18a7-7e71-941b-ebbf14137eee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e64ef-18a7-7f2a-95be-d70467845752" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e64ef-18a7-7e71-941b-ebbf14137eee" xlink:to="loc_us-gaap_EquityComponentDomain_019e64ef-18a7-7f2a-95be-d70467845752" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-18a7-7064-9340-13a64423bb7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e64ef-18a7-7f2a-95be-d70467845752" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-18a7-7064-9340-13a64423bb7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e64ef-18a7-767a-abc7-07acca41e931" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-18a7-7064-9340-13a64423bb7e" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e64ef-18a7-767a-abc7-07acca41e931" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e64ef-18a7-7478-ac5f-e35e25253e60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e64ef-18a7-7064-9340-13a64423bb7e" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e64ef-18a7-7478-ac5f-e35e25253e60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e64ef-18a7-7094-9383-15efa44e5bc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e64ef-18a7-7441-b881-81b799d2e6df" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e64ef-18a7-7094-9383-15efa44e5bc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-18a7-7992-bf7d-c04e045e70a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e64ef-18a7-7094-9383-15efa44e5bc9" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-18a7-7992-bf7d-c04e045e70a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e64ef-18a7-7f43-a33b-c54bff377c18" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e64ef-18a7-7094-9383-15efa44e5bc9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e64ef-18a7-7f43-a33b-c54bff377c18" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e64ef-18a7-7bf2-9fef-05e31151210e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e64ef-18a7-7094-9383-15efa44e5bc9" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e64ef-18a7-7bf2-9fef-05e31151210e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e64ef-18a7-74aa-89fd-1e899a1c1191" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/LeasesAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#LeasesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/LeasesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7f2b-91e0-73101ba5b499" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7f2b-91e0-73101ba5b499" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7059-ab12-7d9606fa3b60" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7f2b-91e0-73101ba5b499" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7059-ab12-7d9606fa3b60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7059-ab12-7d9606fa3b60_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7059-ab12-7d9606fa3b60" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7059-ab12-7d9606fa3b60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7b35-a910-4c9bb17cfb93" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e64ef-18a7-7059-ab12-7d9606fa3b60" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7b35-a910-4c9bb17cfb93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-7dc8-a97d-25fc885c0764" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e64ef-18a7-7b35-a910-4c9bb17cfb93" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e64ef-18a7-7dc8-a97d-25fc885c0764" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e64ef-18a7-743a-8558-bc3f4f82c266" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7f2b-91e0-73101ba5b499" xlink:to="loc_dei_LegalEntityAxis_019e64ef-18a7-743a-8558-bc3f4f82c266" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-743a-8558-bc3f4f82c266_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-743a-8558-bc3f4f82c266" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-743a-8558-bc3f4f82c266_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e64ef-18a7-72c6-83ce-c3aaa3905f78" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e64ef-18a7-743a-8558-bc3f4f82c266" xlink:to="loc_dei_EntityDomain_019e64ef-18a7-72c6-83ce-c3aaa3905f78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7e6c-bf3e-e8094d3a0f3b" xlink:href="pnw-20260630.xsd#pnw_ArizonaPublicServiceCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e64ef-18a7-72c6-83ce-c3aaa3905f78" xlink:to="loc_pnw_ArizonaPublicServiceCompanyMember_019e64ef-18a7-7e6c-bf3e-e8094d3a0f3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfLeaseAgreementsLeaseAndSellBack_019e64ef-18a7-7dfa-9a32-3f393ddc2f07" xlink:href="pnw-20260630.xsd#pnw_NumberOfLeaseAgreementsLeaseAndSellBack"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_pnw_NumberOfLeaseAgreementsLeaseAndSellBack_019e64ef-18a7-7dfa-9a32-3f393ddc2f07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVIELessorTrustsAcquired_019e64ef-18a7-7e92-be17-08891fa227ef" xlink:href="pnw-20260630.xsd#pnw_NumberOfVIELessorTrustsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_pnw_NumberOfVIELessorTrustsAcquired_019e64ef-18a7-7e92-be17-08891fa227ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfVieLessorTrusts_019e64ef-18a7-7dc5-9606-e8b38a43f8e8" xlink:href="pnw-20260630.xsd#pnw_NumberOfVieLessorTrusts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_pnw_NumberOfVieLessorTrusts_019e64ef-18a7-7dc5-9606-e8b38a43f8e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_NumberOfLeaseAgreementsModified_019e64ef-18a7-7056-9e98-93c0e467e7b4" xlink:href="pnw-20260630.xsd#pnw_NumberOfLeaseAgreementsModified"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_pnw_NumberOfLeaseAgreementsModified_019e64ef-18a7-7056-9e98-93c0e467e7b4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_019e64ef-18a7-7346-b682-cc7e6c7ca048" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_019e64ef-18a7-7346-b682-cc7e6c7ca048" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019e64ef-18a7-78d7-8562-0353573ae8ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79f3-957a-daae81263528" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019e64ef-18a7-78d7-8562-0353573ae8ba" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/LeasesScheduleofLeaseCostsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#LeasesScheduleofLeaseCostsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/LeasesScheduleofLeaseCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-7d71-bf5a-1d40487d1a73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7208-9981-ce2dc45725be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-7d71-bf5a-1d40487d1a73" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7208-9981-ce2dc45725be" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-7708-84cf-62bba8a2f6ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-7208-9981-ce2dc45725be" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-7708-84cf-62bba8a2f6ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-7708-84cf-62bba8a2f6ec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-7708-84cf-62bba8a2f6ec" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-7708-84cf-62bba8a2f6ec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-7756-8e79-15c38cbfd219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-7708-84cf-62bba8a2f6ec" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-7756-8e79-15c38cbfd219" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PurchasedPowerLeaseContractsMember_019e64ef-18a7-7973-865f-0457ab941168" xlink:href="pnw-20260630.xsd#pnw_PurchasedPowerLeaseContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-7756-8e79-15c38cbfd219" xlink:to="loc_pnw_PurchasedPowerLeaseContractsMember_019e64ef-18a7-7973-865f-0457ab941168" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LandPropertyandEquipmentLeasesMember_019e64ef-18a7-7f06-88c0-2f1ce966668f" xlink:href="pnw-20260630.xsd#pnw_LandPropertyandEquipmentLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-7756-8e79-15c38cbfd219" xlink:to="loc_pnw_LandPropertyandEquipmentLeasesMember_019e64ef-18a7-7f06-88c0-2f1ce966668f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_019e64ef-18a7-7288-8002-6b30d6330670" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-7d71-bf5a-1d40487d1a73" xlink:to="loc_us-gaap_OperatingLeaseCost_019e64ef-18a7-7288-8002-6b30d6330670" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_019e64ef-18a7-7464-9075-255e789c7fc4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-7d71-bf5a-1d40487d1a73" xlink:to="loc_us-gaap_VariableLeaseCost_019e64ef-18a7-7464-9075-255e789c7fc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_019e64ef-18a7-7166-afea-afdbc3d3df72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-7d71-bf5a-1d40487d1a73" xlink:to="loc_us-gaap_ShortTermLeaseCost_019e64ef-18a7-7166-afea-afdbc3d3df72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_019e64ef-18a7-77b6-b7d3-ae6e70fde776" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-7d71-bf5a-1d40487d1a73" xlink:to="loc_us-gaap_LeaseCost_019e64ef-18a7-77b6-b7d3-ae6e70fde776" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/LeasesScheduleofMaturityofOurOperatingLeaseLiabilitiesDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#LeasesScheduleofMaturityofOurOperatingLeaseLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/LeasesScheduleofMaturityofOurOperatingLeaseLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-756c-88be-265ca6b9ae6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-756c-88be-265ca6b9ae6f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-77db-92fd-332adb539a82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019e64ef-18a7-756c-88be-265ca6b9ae6f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-77db-92fd-332adb539a82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-77db-92fd-332adb539a82_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-77db-92fd-332adb539a82" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-77db-92fd-332adb539a82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-77ba-a854-0ff709ad0205" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e64ef-18a7-77db-92fd-332adb539a82" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-77ba-a854-0ff709ad0205" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_PurchasedPowerLeaseContractsMember_019e64ef-18a7-7608-beb2-1c83c5a429c3" xlink:href="pnw-20260630.xsd#pnw_PurchasedPowerLeaseContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-77ba-a854-0ff709ad0205" xlink:to="loc_pnw_PurchasedPowerLeaseContractsMember_019e64ef-18a7-7608-beb2-1c83c5a429c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_LandPropertyandEquipmentLeasesMember_019e64ef-18a7-78a1-87fd-3af2af02c528" xlink:href="pnw-20260630.xsd#pnw_LandPropertyandEquipmentLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e64ef-18a7-77ba-a854-0ff709ad0205" xlink:to="loc_pnw_LandPropertyandEquipmentLeasesMember_019e64ef-18a7-78a1-87fd-3af2af02c528" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_019e64ef-18a7-7fa1-9347-e088b6ce20ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_019e64ef-18a7-7fa1-9347-e088b6ce20ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_019e64ef-18a7-7b6e-a0a6-46788ebaaf8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_019e64ef-18a7-7b6e-a0a6-46788ebaaf8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_019e64ef-18a7-7d6c-b057-cba546c7e36b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_019e64ef-18a7-7d6c-b057-cba546c7e36b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_019e64ef-18a7-7090-aef5-67c639fd8eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_019e64ef-18a7-7090-aef5-67c639fd8eb7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_019e64ef-18a7-7cd0-a2ca-f99eda8a83e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_019e64ef-18a7-7cd0-a2ca-f99eda8a83e5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_019e64ef-18a7-7ddc-b89b-640a3991235c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_019e64ef-18a7-7ddc-b89b-640a3991235c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_019e64ef-18a7-780d-83e2-18746211f3dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_019e64ef-18a7-780d-83e2-18746211f3dd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019e64ef-18a7-7372-8c33-5d1390f88b44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019e64ef-18a7-7372-8c33-5d1390f88b44" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_019e64ef-18a7-7ddb-ab82-4abef027dd5f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_019e64ef-18a7-7ddb-ab82-4abef027dd5f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_019e64ef-18a7-78e4-9956-5f27cc812842" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019e64ef-18a7-79e1-be1c-f81aca11d407" xlink:to="loc_us-gaap_OperatingLeaseLiability_019e64ef-18a7-78e4-9956-5f27cc812842" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ElDoradoEquityInvestmentsScheduleofElDoradosOwnershipPercentagesandCarryingValueofInvestmentsAccountedforUndertheEquityMethodInvestmentsDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#ElDoradoEquityInvestmentsScheduleofElDoradosOwnershipPercentagesandCarryingValueofInvestmentsAccountedforUndertheEquityMethodInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ElDoradoEquityInvestmentsScheduleofElDoradosOwnershipPercentagesandCarryingValueofInvestmentsAccountedforUndertheEquityMethodInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-761d-8a03-4696999e616f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-7af4-9cde-f079624f3f99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-761d-8a03-4696999e616f" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-7af4-9cde-f079624f3f99" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-7235-b1f4-fbd764931444" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-7af4-9cde-f079624f3f99" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-7235-b1f4-fbd764931444" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7235-b1f4-fbd764931444_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-7235-b1f4-fbd764931444" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7235-b1f4-fbd764931444_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7076-82b2-3f67b1635ead" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-7235-b1f4-fbd764931444" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7076-82b2-3f67b1635ead" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SAIAdvancedPowerSolutionsIncMember_019e64ef-18a7-7404-9aa2-c6adfde2223e" xlink:href="pnw-20260630.xsd#pnw_SAIAdvancedPowerSolutionsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7076-82b2-3f67b1635ead" xlink:to="loc_pnw_SAIAdvancedPowerSolutionsIncMember_019e64ef-18a7-7404-9aa2-c6adfde2223e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_CopperSkyMember_019e64ef-18a7-759b-9059-b22ea82ee3ce" xlink:href="pnw-20260630.xsd#pnw_CopperSkyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7076-82b2-3f67b1635ead" xlink:to="loc_pnw_CopperSkyMember_019e64ef-18a7-759b-9059-b22ea82ee3ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_019e64ef-18a7-7d73-9019-ad5ad587ef0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-761d-8a03-4696999e616f" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_019e64ef-18a7-7d73-9019-ad5ad587ef0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_019e64ef-18a7-7052-9ee8-1255147298f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-761d-8a03-4696999e616f" xlink:to="loc_us-gaap_EquityMethodInvestments_019e64ef-18a7-7052-9ee8-1255147298f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_EquityMethodInvestmentFundingCommitmentTotalAmount_019e64ef-18a7-7c30-aa7e-95a6c6b19b34" xlink:href="pnw-20260630.xsd#pnw_EquityMethodInvestmentFundingCommitmentTotalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-761d-8a03-4696999e616f" xlink:to="loc_pnw_EquityMethodInvestmentFundingCommitmentTotalAmount_019e64ef-18a7-7c30-aa7e-95a6c6b19b34" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_EquityMethodInvestmentFundingCommitmentAmountFunded_019e64ef-18a7-77c0-aeac-48e781eee670" xlink:href="pnw-20260630.xsd#pnw_EquityMethodInvestmentFundingCommitmentAmountFunded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-761d-8a03-4696999e616f" xlink:to="loc_pnw_EquityMethodInvestmentFundingCommitmentAmountFunded_019e64ef-18a7-77c0-aeac-48e781eee670" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pinnaclewest.com/role/ElDoradoEquityInvestmentsAdditionalInformationDetails" xlink:type="simple" xlink:href="pnw-20260630.xsd#ElDoradoEquityInvestmentsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pinnaclewest.com/role/ElDoradoEquityInvestmentsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7258-a304-8746ff90b5be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-70ac-8223-8a7250d9d472" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7258-a304-8746ff90b5be" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-70ac-8223-8a7250d9d472" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-797c-87cb-572b2373bfac" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e64ef-18a7-70ac-8223-8a7250d9d472" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-797c-87cb-572b2373bfac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-797c-87cb-572b2373bfac_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-797c-87cb-572b2373bfac" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-797c-87cb-572b2373bfac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7e2a-89ee-aacbf98bfa0c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e64ef-18a7-797c-87cb-572b2373bfac" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7e2a-89ee-aacbf98bfa0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SAICopperSkyMember_019e64ef-18a7-79ba-9165-d405eb9a12cf" xlink:href="pnw-20260630.xsd#pnw_SAICopperSkyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e64ef-18a7-7e2a-89ee-aacbf98bfa0c" xlink:to="loc_pnw_SAICopperSkyMember_019e64ef-18a7-79ba-9165-d405eb9a12cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnw_SAIAdvancedPowerSolutionsIncMember_019f94aa-a5bb-7bf6-adc0-a92cd5deb506" xlink:href="pnw-20260630.xsd#pnw_SAIAdvancedPowerSolutionsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnw_SAICopperSkyMember_019e64ef-18a7-79ba-9165-d405eb9a12cf" xlink:to="loc_pnw_SAIAdvancedPowerSolutionsIncMember_019f94aa-a5bb-7bf6-adc0-a92cd5deb506" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_019f94aa-0a3e-730e-9d1e-cda8f804b17c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7258-a304-8746ff90b5be" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_019f94aa-0a3e-730e-9d1e-cda8f804b17c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019e64ef-18a7-72c9-b07f-ce5ab8230235" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7258-a304-8746ff90b5be" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019e64ef-18a7-72c9-b07f-ce5ab8230235" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019e64ef-18a7-7a74-be92-f593f880fa43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e64ef-18a7-7258-a304-8746ff90b5be" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019e64ef-18a7-7a74-be92-f593f880fa43" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
