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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019fc884-1a15-7bc0-9ed4-bfdfaa6eb588,g:68fdc1b1-a26a-44d4-abfc-56efb5f676b7-->
<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://www.idacorpinc.com/role/Cover" xlink:type="simple" xlink:href="ida-20260930.xsd#Cover"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_019fc884-1c1d-74c7-a2f0-2618111f6c37" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentInformationTable_019fc884-1c1d-74c7-a2f0-2618111f6c37" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-72e7-bb8e-5b3ac57d3313" 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_DocumentInformationTable_019fc884-1c1d-74c7-a2f0-2618111f6c37" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-72e7-bb8e-5b3ac57d3313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-72e7-bb8e-5b3ac57d3313_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_019fc884-1c1d-72e7-bb8e-5b3ac57d3313" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-72e7-bb8e-5b3ac57d3313_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7f77-9067-cc06bb7ee9db" 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_019fc884-1c1d-72e7-bb8e-5b3ac57d3313" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7f77-9067-cc06bb7ee9db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7919-b3c5-a68dd1c62cb4" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-7f77-9067-cc06bb7ee9db" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7919-b3c5-a68dd1c62cb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_NoTradingSymbolFlag_019fc884-1c1d-71a5-860a-b790e161fa2e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_NoTradingSymbolFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_NoTradingSymbolFlag_019fc884-1c1d-71a5-860a-b790e161fa2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019fc884-1c1d-78d7-892c-694fa3139005" 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_dei_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_us-gaap_NumberOfReportableSegments_019fc884-1c1d-78d7-892c-694fa3139005" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_019fc884-1c1d-713b-98a8-c4db94f5149f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_us-gaap_NumberOfOperatingSegments_019fc884-1c1d-713b-98a8-c4db94f5149f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019fc884-1c1d-7dbd-a45a-28ea3db64959" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentType_019fc884-1c1d-7dbd-a45a-28ea3db64959" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_019fc884-1c1d-7814-899d-aac7b22c2d5b" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentQuarterlyReport_019fc884-1c1d-7814-899d-aac7b22c2d5b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019fc884-1c1d-73da-a9a5-8c140da76c1a" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentPeriodEndDate_019fc884-1c1d-73da-a9a5-8c140da76c1a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019fc884-1c1d-7523-9ea9-fa74e1b734cb" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentTransitionReport_019fc884-1c1d-7523-9ea9-fa74e1b734cb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019fc884-1c1d-7c9a-b72c-bb31211937e7" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityFileNumber_019fc884-1c1d-7c9a-b72c-bb31211937e7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019fc884-1c1d-7f17-b3b7-2446d7a95c87" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityRegistrantName_019fc884-1c1d-7f17-b3b7-2446d7a95c87" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019fc884-1c1d-7fdd-a1e4-60acbf23f42c" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityTaxIdentificationNumber_019fc884-1c1d-7fdd-a1e4-60acbf23f42c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019fc884-1c1d-791e-ad1b-4f880d676970" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityAddressAddressLine1_019fc884-1c1d-791e-ad1b-4f880d676970" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019fc884-1c1d-772d-ae4b-923cde3f49bc" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityAddressCityOrTown_019fc884-1c1d-772d-ae4b-923cde3f49bc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019fc884-1c1d-7a5e-ac25-75aa6ea874ed" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityAddressStateOrProvince_019fc884-1c1d-7a5e-ac25-75aa6ea874ed" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019fc884-1c1d-7552-9250-e2a95126a837" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityAddressPostalZipCode_019fc884-1c1d-7552-9250-e2a95126a837" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019fc884-1c1d-7d71-a932-edf1604cd45d" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_CityAreaCode_019fc884-1c1d-7d71-a932-edf1604cd45d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019fc884-1c1d-7d5e-b3b5-254507f06e01" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_LocalPhoneNumber_019fc884-1c1d-7d5e-b3b5-254507f06e01" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019fc884-1c1d-7d49-b46d-5471c7720964" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityCurrentReportingStatus_019fc884-1c1d-7d49-b46d-5471c7720964" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019fc884-1c1d-7b4c-be5c-9dc7db868998" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019fc884-1c1d-7b4c-be5c-9dc7db868998" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019fc884-1c1d-7e7e-8993-6d238c1fdfa5" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityInteractiveDataCurrent_019fc884-1c1d-7e7e-8993-6d238c1fdfa5" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019fc884-1c1d-7191-87e3-4fa5db39faa5" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityFilerCategory_019fc884-1c1d-7191-87e3-4fa5db39faa5" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_019fc884-1c1d-755f-8a68-44621e1b24bc" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntitySmallBusiness_019fc884-1c1d-755f-8a68-44621e1b24bc" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019fc884-1c1d-7c29-941b-ca20ed7f800e" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityEmergingGrowthCompany_019fc884-1c1d-7c29-941b-ca20ed7f800e" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019fc884-1c1d-7650-b6f7-1edcdc0ce181" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityShellCompany_019fc884-1c1d-7650-b6f7-1edcdc0ce181" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019fc884-1c1d-7ecd-8647-dafe8913f707" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_Security12bTitle_019fc884-1c1d-7ecd-8647-dafe8913f707" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019fc884-1c1d-7554-a5a8-cb94e871f748" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_TradingSymbol_019fc884-1c1d-7554-a5a8-cb94e871f748" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019fc884-1c1d-7e71-96b4-71d7c6ce5227" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_SecurityExchangeName_019fc884-1c1d-7e71-96b4-71d7c6ce5227" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019fc884-1c1d-7a13-85c9-bd398f065d30" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019fc884-1c1d-7a13-85c9-bd398f065d30" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019fc884-1c1d-7be9-b891-eb5b90d77266" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityCentralIndexKey_019fc884-1c1d-7be9-b891-eb5b90d77266" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019fc884-1c1d-76cf-bdd0-c1c194545c51" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_CurrentFiscalYearEndDate_019fc884-1c1d-76cf-bdd0-c1c194545c51" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019fc884-1c1d-7b5d-a776-59e74410a521" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentFiscalYearFocus_019fc884-1c1d-7b5d-a776-59e74410a521" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019fc884-1c1d-7c22-971a-eb4e6dd77d6d" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019fc884-1c1d-7c22-971a-eb4e6dd77d6d" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019fc884-1c1d-791a-8bad-c846873bb731" 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_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_AmendmentFlag_019fc884-1c1d-791a-8bad-c846873bb731" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationFormerLegalOrRegisteredName_019fc884-1c1d-7fa9-8848-522207a8cf66" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInformationFormerLegalOrRegisteredName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019fc884-1c1d-7d66-8cfc-5f61dbb947f9" xlink:to="loc_dei_EntityInformationFormerLegalOrRegisteredName_019fc884-1c1d-7fa9-8848-522207a8cf66" xlink:type="arc" order="32"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/ConsolidatedStatementsofEquity" xlink:type="simple" xlink:href="ida-20260930.xsd#ConsolidatedStatementsofEquity"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/ConsolidatedStatementsofEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-76de-ba1d-bad4f63defee" 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_019fc884-1c1d-73b6-8204-d3135920e066" 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_019fc884-1c1d-76de-ba1d-bad4f63defee" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-73b6-8204-d3135920e066" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019fc884-1c1d-7d15-b021-a510aa8ca75e" 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_019fc884-1c1d-73b6-8204-d3135920e066" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019fc884-1c1d-7d15-b021-a510aa8ca75e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fc884-1c1d-7d15-b021-a510aa8ca75e_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_019fc884-1c1d-7d15-b021-a510aa8ca75e" xlink:to="loc_us-gaap_EquityComponentDomain_019fc884-1c1d-7d15-b021-a510aa8ca75e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fc884-1c1d-7752-b235-5fa3100dc6d1" 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_019fc884-1c1d-7d15-b021-a510aa8ca75e" xlink:to="loc_us-gaap_EquityComponentDomain_019fc884-1c1d-7752-b235-5fa3100dc6d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019fc884-1c1d-7ed0-b85a-a14ef54a71b2" 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_019fc884-1c1d-7752-b235-5fa3100dc6d1" xlink:to="loc_us-gaap_CommonStockMember_019fc884-1c1d-7ed0-b85a-a14ef54a71b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember_019fc884-1c1d-7308-a953-2a08722ea36b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fc884-1c1d-7752-b235-5fa3100dc6d1" xlink:to="loc_us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember_019fc884-1c1d-7308-a953-2a08722ea36b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019fc884-1c1d-7470-ad09-3b372aa29087" 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_019fc884-1c1d-7752-b235-5fa3100dc6d1" xlink:to="loc_us-gaap_RetainedEarningsMember_019fc884-1c1d-7470-ad09-3b372aa29087" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fc884-1c1d-7b16-bae6-3f773c99b7c6" 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_019fc884-1c1d-7752-b235-5fa3100dc6d1" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fc884-1c1d-7b16-bae6-3f773c99b7c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019fc884-1c1d-7695-be7b-56eb5df231e9" 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_019fc884-1c1d-7752-b235-5fa3100dc6d1" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019fc884-1c1d-7695-be7b-56eb5df231e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" 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_019fc884-1c1d-76de-ba1d-bad4f63defee" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019fc884-1c1d-7eb4-a97b-3cb3939c5858" 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_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019fc884-1c1d-7eb4-a97b-3cb3939c5858" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_019fc884-1c1d-7e24-ae36-5571986e2893" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_019fc884-1c1d-7e24-ae36-5571986e2893" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fc884-1c1d-733f-95e5-6ba6ca41b450" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fc884-1c1d-733f-95e5-6ba6ca41b450" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019fc884-1c1d-7cf0-b296-2b806ad56350" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019fc884-1c1d-7cf0-b296-2b806ad56350" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_019fc884-1c1d-747d-ab1e-87bc59910e95" 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_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_StockholdersEquityOther_019fc884-1c1d-747d-ab1e-87bc59910e95" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fc884-1c1d-7832-ac17-000b5e52a755" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_NetIncomeLoss_019fc884-1c1d-7832-ac17-000b5e52a755" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_019fc884-1c1d-7157-b08c-c79f34286e8e" 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_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_DividendsCommonStockCash_019fc884-1c1d-7157-b08c-c79f34286e8e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019fc884-1c1d-79b2-aff7-0a6f248c3628" 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_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019fc884-1c1d-79b2-aff7-0a6f248c3628" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fc884-1c1d-7c75-96a2-b15f4e6514ac" 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_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_StockholdersEquity_019fc884-1c1d-7c75-96a2-b15f4e6514ac" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019fc884-1c1d-7fb5-b2db-b7596895c350" 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_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1c1d-7411-9a20-67256ac56553" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019fc884-1c1d-7fb5-b2db-b7596895c350" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019fc884-1c1d-7e1b-b8bd-924eb6cb4cc4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedStatementsofIncome" xlink:type="simple" xlink:href="ida-20260930.xsd#IdahoPowerCompanyConsolidatedStatementsofIncome"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedStatementsofIncome" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-7897-ad16-86bec6850abb" 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_019fc884-1c1d-7f51-a5ec-efc374ae842b" 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_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-7f51-a5ec-efc374ae842b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-76f2-9abf-e770249952e4" 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_019fc884-1c1d-7f51-a5ec-efc374ae842b" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-76f2-9abf-e770249952e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-76f2-9abf-e770249952e4_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_019fc884-1c1d-76f2-9abf-e770249952e4" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-76f2-9abf-e770249952e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7943-aff6-64e76f95db53" 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_019fc884-1c1d-76f2-9abf-e770249952e4" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7943-aff6-64e76f95db53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-72ab-a062-59e11ea8bb17" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-7943-aff6-64e76f95db53" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-72ab-a062-59e11ea8bb17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatedOperatingRevenueAbstract_019fc884-1c1d-7563-8bd0-e2a4d86501ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatedOperatingRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_RegulatedOperatingRevenueAbstract_019fc884-1c1d-7563-8bd0-e2a4d86501ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatedOperatingRevenueElectricNonNuclear_019fc884-1c1d-7861-9298-3b23478cff74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatedOperatingRevenueElectricNonNuclear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatedOperatingRevenueAbstract_019fc884-1c1d-7563-8bd0-e2a4d86501ac" xlink:to="loc_us-gaap_RegulatedOperatingRevenueElectricNonNuclear_019fc884-1c1d-7861-9298-3b23478cff74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpensePurchasedPower_019fc884-1c1d-7ce9-81a7-d31d70805458" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpensePurchasedPower"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_us-gaap_UtilitiesOperatingExpensePurchasedPower_019fc884-1c1d-7ce9-81a7-d31d70805458" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseFuelUsed_019fc884-1c1d-771e-af63-4953e57d7f69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpenseFuelUsed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseFuelUsed_019fc884-1c1d-771e-af63-4953e57d7f69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Powercostadjustmentexpensedeferral_019fc884-1c1d-713a-b824-552b8d8716e1" xlink:href="ida-20260930.xsd#ida_Powercostadjustmentexpensedeferral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_ida_Powercostadjustmentexpensedeferral_019fc884-1c1d-713a-b824-552b8d8716e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations_019fc884-1c1d-7660-b601-ded62f7dde69" 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_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations_019fc884-1c1d-7660-b601-ded62f7dde69" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_EnergyEfficiencyPrograms_019fc884-1c1d-7fb8-96a0-662bee3636e3" xlink:href="ida-20260930.xsd#ida_EnergyEfficiencyPrograms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_ida_EnergyEfficiencyPrograms_019fc884-1c1d-7fb8-96a0-662bee3636e3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseDepreciationAndAmortization_019fc884-1c1d-7286-b8dc-d828b420b127" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpenseDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseDepreciationAndAmortization_019fc884-1c1d-7286-b8dc-d828b420b127" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_UtilitiesOperatingExpenseOtherNet_019fc884-1c1d-71de-8a41-b5953efaffc5" xlink:href="ida-20260930.xsd#ida_UtilitiesOperatingExpenseOtherNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_ida_UtilitiesOperatingExpenseOtherNet_019fc884-1c1d-71de-8a41-b5953efaffc5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpense_019fc884-1c1d-759f-8671-d49b1b608b6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019fc884-1c1d-7c30-8e50-2fcc2d2e2c80" xlink:to="loc_us-gaap_UtilitiesOperatingExpense_019fc884-1c1d-759f-8671-d49b1b608b6d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019fc884-1c1d-7f9f-94c0-6080a634c34d" 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_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_OperatingIncomeLoss_019fc884-1c1d-7f9f-94c0-6080a634c34d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" 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_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019fc884-1c1d-7a5d-869a-268d97e35a52" 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_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity_019fc884-1c1d-7a5d-869a-268d97e35a52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019fc884-1c1d-79fa-9f41-2142877f4647" 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_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019fc884-1c1d-79fa-9f41-2142877f4647" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019fc884-1c1d-72cd-a947-8852ef267b62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_InterestExpenseDebt_019fc884-1c1d-72cd-a947-8852ef267b62" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOther_019fc884-1c1d-77fa-bd7c-5f1a1073cdd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_InterestExpenseOther_019fc884-1c1d-77fa-bd7c-5f1a1073cdd5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestCostsCapitalizedAdjustment_019fc884-1c1d-7e81-990d-c5f201b12c54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestCostsCapitalizedAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_InterestCostsCapitalizedAdjustment_019fc884-1c1d-7e81-990d-c5f201b12c54" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019fc884-1c1d-7390-9a0c-61dc70619dfd" 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_NonoperatingIncomeExpenseAbstract_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019fc884-1c1d-7390-9a0c-61dc70619dfd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019fc884-1c1d-7a27-be01-bb49957f76d4" 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_019fc884-1c1d-7904-a484-74074f2fe278" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019fc884-1c1d-7a27-be01-bb49957f76d4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019fc884-1c1d-74f3-96b6-722f8981f74d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019fc884-1c1d-74f3-96b6-722f8981f74d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019fc884-1c1d-7060-9e00-f03c0aa6033c" 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_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019fc884-1c1d-7060-9e00-f03c0aa6033c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019fc884-1c1d-7882-b512-91887f925495" 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_019fc884-1c1d-7897-ad16-86bec6850abb" xlink:to="loc_us-gaap_ProfitLoss_019fc884-1c1d-7882-b512-91887f925495" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedStatementsofComprehensiveIncome" xlink:type="simple" xlink:href="ida-20260930.xsd#IdahoPowerCompanyConsolidatedStatementsofComprehensiveIncome"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedStatementsofComprehensiveIncome" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-749b-a289-4efb8f03f78d" 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_019fc884-1c1d-7963-8f90-336dbea4b903" 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_019fc884-1c1d-749b-a289-4efb8f03f78d" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-7963-8f90-336dbea4b903" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-7eed-b6b7-b1a37b2971ff" 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_019fc884-1c1d-7963-8f90-336dbea4b903" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-7eed-b6b7-b1a37b2971ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7eed-b6b7-b1a37b2971ff_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_019fc884-1c1d-7eed-b6b7-b1a37b2971ff" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7eed-b6b7-b1a37b2971ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-74ff-82d1-575588abb1a6" 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_019fc884-1c1d-7eed-b6b7-b1a37b2971ff" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-74ff-82d1-575588abb1a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-764a-a2c5-535f65145fd2" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-74ff-82d1-575588abb1a6" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-764a-a2c5-535f65145fd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019fc884-1c1d-7a88-9c92-e7ccd8db5c7c" 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_019fc884-1c1d-749b-a289-4efb8f03f78d" xlink:to="loc_us-gaap_ProfitLoss_019fc884-1c1d-7a88-9c92-e7ccd8db5c7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_019fc884-1c1d-7862-bcfa-540ed9479fce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-749b-a289-4efb8f03f78d" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_019fc884-1c1d-7862-bcfa-540ed9479fce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019fc884-1c1d-73c9-8f98-a9e614fd1a6e" 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_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_019fc884-1c1d-7862-bcfa-540ed9479fce" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019fc884-1c1d-73c9-8f98-a9e614fd1a6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019fc884-1c1d-742c-9fc9-64a5da98a26f" 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_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_019fc884-1c1d-7862-bcfa-540ed9479fce" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019fc884-1c1d-742c-9fc9-64a5da98a26f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedBalanceSheet" xlink:type="simple" xlink:href="ida-20260930.xsd#IdahoPowerCompanyConsolidatedBalanceSheet"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedBalanceSheet" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" 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_019fc884-1c1d-7527-86a5-c18f65f1bf28" 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_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-7527-86a5-c18f65f1bf28" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-7e3a-ba67-79462f2332d6" 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_019fc884-1c1d-7527-86a5-c18f65f1bf28" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-7e3a-ba67-79462f2332d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7e3a-ba67-79462f2332d6_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_019fc884-1c1d-7e3a-ba67-79462f2332d6" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7e3a-ba67-79462f2332d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-78a9-8654-792c05c75c75" 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_019fc884-1c1d-7e3a-ba67-79462f2332d6" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-78a9-8654-792c05c75c75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7dff-9903-70b2cbe75cbe" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-78a9-8654-792c05c75c75" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7dff-9903-70b2cbe75cbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fc884-1c1d-7c60-9b65-261e2f36b651" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019fc884-1c1d-7527-86a5-c18f65f1bf28" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fc884-1c1d-7c60-9b65-261e2f36b651" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019fc884-1c1d-7c60-9b65-261e2f36b651_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fc884-1c1d-7c60-9b65-261e2f36b651" xlink:to="loc_us-gaap_RelatedPartyDomain_019fc884-1c1d-7c60-9b65-261e2f36b651_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019fc884-1c1d-7a46-bb99-1f97d32c15b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fc884-1c1d-7c60-9b65-261e2f36b651" xlink:to="loc_us-gaap_RelatedPartyDomain_019fc884-1c1d-7a46-bb99-1f97d32c15b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOfCommonParentMember_019fc884-1c1d-7dc3-9f51-184092d719a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiaryOfCommonParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019fc884-1c1d-7a46-bb99-1f97d32c15b5" xlink:to="loc_us-gaap_SubsidiaryOfCommonParentMember_019fc884-1c1d-7dc3-9f51-184092d719a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019fc884-1c1d-72c7-b462-6ab9e360bb9c" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019fc884-1c1d-72c7-b462-6ab9e360bb9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019fc884-1c1d-7309-b48d-a59de17e77f7" 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_019fc884-1c1d-72c7-b462-6ab9e360bb9c" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019fc884-1c1d-7309-b48d-a59de17e77f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesAbstract_019fc884-1c1d-72b1-b507-5ae6cc437f25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivablesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_ReceivablesAbstract_019fc884-1c1d-72b1-b507-5ae6cc437f25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019fc884-1c1d-706e-ab4c-5384dd4cfa66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivablesAbstract_019fc884-1c1d-72b1-b507-5ae6cc437f25" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019fc884-1c1d-706e-ab4c-5384dd4cfa66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherReceivables_019fc884-1c1d-7d26-b4af-e33a9826c266" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivablesAbstract_019fc884-1c1d-72b1-b507-5ae6cc437f25" xlink:to="loc_us-gaap_OtherReceivables_019fc884-1c1d-7d26-b4af-e33a9826c266" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_019fc884-1c1d-7362-b31a-2b40ed8490b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_IncomeTaxesReceivable_019fc884-1c1d-7362-b31a-2b40ed8490b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnbilledReceivablesCurrent_019fc884-1c1d-74ba-9311-0ea9dfcefa40" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnbilledReceivablesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_UnbilledReceivablesCurrent_019fc884-1c1d-74ba-9311-0ea9dfcefa40" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherInventorySupplies_019fc884-1c1d-7754-82de-19bb4c274450" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_OtherInventorySupplies_019fc884-1c1d-7754-82de-19bb4c274450" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedInventoryOtherFossilFuel_019fc884-1c1d-7968-9b03-8e2bbec509a3" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_EnergyRelatedInventoryOtherFossilFuel_019fc884-1c1d-7968-9b03-8e2bbec509a3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseCurrent_019fc884-1c1d-7219-816f-004ddacd1c80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_PrepaidExpenseCurrent_019fc884-1c1d-7219-816f-004ddacd1c80" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsCurrent_019fc884-1c1d-7de4-ab85-d75b1c3a2e00" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_RegulatoryAssetsCurrent_019fc884-1c1d-7de4-ab85-d75b1c3a2e00" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_019fc884-1c1d-7f77-b8c9-de65b8882b17" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_019fc884-1c1d-7f77-b8c9-de65b8882b17" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_019fc884-1c1d-703d-ad7c-68fab488ffb5" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_OtherAssetsCurrent_019fc884-1c1d-703d-ad7c-68fab488ffb5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019fc884-1c1d-7d1d-b40e-915086581f43" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_AssetsCurrent_019fc884-1c1d-7d1d-b40e-915086581f43" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_019fc884-1c1d-7e48-a84d-9bb70fcaa1a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_LongTermInvestments_019fc884-1c1d-7e48-a84d-9bb70fcaa1a3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019fc884-1c1d-7e29-8986-9e2a4dc3bacb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019fc884-1c1d-7e29-8986-9e2a4dc3bacb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_019fc884-1c1d-713b-809a-3be4c2673730" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_019fc884-1c1d-713b-809a-3be4c2673730" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019fc884-1c1d-7919-a7c4-1efbd9d80c51" 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_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019fc884-1c1d-7919-a7c4-1efbd9d80c51" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressGross_019fc884-1c1d-7541-866b-d9afe528b3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConstructionInProgressGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_ConstructionInProgressGross_019fc884-1c1d-7541-866b-d9afe528b3ba" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAsset_019fc884-1c1d-7a9d-9c06-c5cb33742433" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAsset_019fc884-1c1d-7a9d-9c06-c5cb33742433" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlantHeldForFutureUseAmount_019fc884-1c1d-7465-a226-659935a4296b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlantHeldForFutureUseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_PlantHeldForFutureUseAmount_019fc884-1c1d-7465-a226-659935a4296b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOther_019fc884-1c1d-79e0-b730-79cfa53452d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOther_019fc884-1c1d-79e0-b730-79cfa53452d9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019fc884-1c1d-7004-b76d-caf6ad5198fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_019fc884-1c1d-747e-b73a-ecce8ff5eb5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019fc884-1c1d-7004-b76d-caf6ad5198fd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNoncurrentAbstract_019fc884-1c1d-7d6c-a6fc-9b4e1b6d9261" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_AssetsNoncurrentAbstract_019fc884-1c1d-7d6c-a6fc-9b4e1b6d9261" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount_019fc884-1c1d-7c9e-ad8c-3c372e8d63c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LifeInsuranceCorporateOrBankOwnedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsNoncurrentAbstract_019fc884-1c1d-7d6c-a6fc-9b4e1b6d9261" xlink:to="loc_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount_019fc884-1c1d-7c9e-ad8c-3c372e8d63c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsNoncurrent_019fc884-1c1d-7625-ada9-4fce7558ac9d" 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_AssetsNoncurrentAbstract_019fc884-1c1d-7d6c-a6fc-9b4e1b6d9261" xlink:to="loc_us-gaap_RegulatoryAssetsNoncurrent_019fc884-1c1d-7625-ada9-4fce7558ac9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019fc884-1c1d-789b-9660-5a9d17ac251d" 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_us-gaap_AssetsNoncurrentAbstract_019fc884-1c1d-7d6c-a6fc-9b4e1b6d9261" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019fc884-1c1d-789b-9660-5a9d17ac251d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment_019fc884-1c1d-7f85-a478-f6aeb93d0fa5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsNoncurrentAbstract_019fc884-1c1d-7d6c-a6fc-9b4e1b6d9261" xlink:to="loc_us-gaap_AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment_019fc884-1c1d-7f85-a478-f6aeb93d0fa5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019fc884-1c1d-7f61-b895-d6823721d4b6" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_Assets_019fc884-1c1d-7f61-b895-d6823721d4b6" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019fc884-1c1d-77e0-92c2-63c860b1e34c" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_LongTermDebtCurrent_019fc884-1c1d-77e0-92c2-63c860b1e34c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019fc884-1c1d-7a32-84c0-03cd95394e2d" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_AccountsPayableCurrent_019fc884-1c1d-7a32-84c0-03cd95394e2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableOtherCurrentAndNoncurrent_019fc884-1c1d-7b9a-a5b9-e45a5b8fcce4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableOtherCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_AccountsPayableOtherCurrentAndNoncurrent_019fc884-1c1d-7b9a-a5b9-e45a5b8fcce4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_019fc884-1c1d-71a3-b3c2-7a670d194736" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_TaxesPayableCurrent_019fc884-1c1d-71a3-b3c2-7a670d194736" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrent_019fc884-1c1d-7549-a703-27f74a2099af" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_InterestPayableCurrent_019fc884-1c1d-7549-a703-27f74a2099af" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_019fc884-1c1d-73bf-ae78-02b652b66a01" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_019fc884-1c1d-73bf-ae78-02b652b66a01" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityCurrent_019fc884-1c1d-763f-b3d8-e8ad0bd9eb6d" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_RegulatoryLiabilityCurrent_019fc884-1c1d-763f-b3d8-e8ad0bd9eb6d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019fc884-1c1d-72f4-aec5-15242c5d16d4" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019fc884-1c1d-72f4-aec5-15242c5d16d4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_019fc884-1c1d-70fe-9eec-483e68e3e924" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_019fc884-1c1d-70fe-9eec-483e68e3e924" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_019fc884-1c1d-779c-adc6-793d491ac679" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_019fc884-1c1d-779c-adc6-793d491ac679" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019fc884-1c1d-7f27-b502-e6657ff688fc" 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_019fc884-1c1d-7e90-b9b1-afc83fb6f48b" xlink:to="loc_us-gaap_LiabilitiesCurrent_019fc884-1c1d-7f27-b502-e6657ff688fc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019fc884-1c1d-7983-8f9d-26c8f968fd50" 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_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019fc884-1c1d-7983-8f9d-26c8f968fd50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityNoncurrent_019fc884-1c1d-7db3-921d-b28eb386cd5e" 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_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:to="loc_us-gaap_RegulatoryLiabilityNoncurrent_019fc884-1c1d-7db3-921d-b28eb386cd5e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_019fc884-1c1d-7637-b0b9-f6454abc3fd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_019fc884-1c1d-7637-b0b9-f6454abc3fd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_FinanceLeaseNonCurrentLiability_019fc884-1c1d-7e0c-839c-2954eaa57c0b" xlink:href="ida-20260930.xsd#ida_FinanceLeaseNonCurrentLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:to="loc_ida_FinanceLeaseNonCurrentLiability_019fc884-1c1d-7e0c-839c-2954eaa57c0b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019fc884-1c1d-74e0-94b9-fe9f360c5109" 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_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019fc884-1c1d-74e0-94b9-fe9f360c5109" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent_019fc884-1c1d-70d2-924a-0a7e9e110078" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesAbstract_019fc884-1c1d-7f9e-83b6-c0315efeaa6a" xlink:to="loc_us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent_019fc884-1c1d-70d2-924a-0a7e9e110078" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019fc884-1c1d-7dca-8b01-80dccda14de5" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019fc884-1c1d-7dca-8b01-80dccda14de5" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019fc884-1c1d-7d8c-a4a7-681bb252ad2c" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019fc884-1c1d-7d8c-a4a7-681bb252ad2c" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019fc884-1c1d-74ae-92bb-b6a3db9948e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:to="loc_us-gaap_CommonStockValue_019fc884-1c1d-74ae-92bb-b6a3db9948e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019fc884-1c1d-7d42-a573-aaf32701f240" 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_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019fc884-1c1d-7d42-a573-aaf32701f240" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CapitalStockIssuanceCosts_019fc884-1c1d-7543-9831-e656ff01e259" xlink:href="ida-20260930.xsd#ida_CapitalStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:to="loc_ida_CapitalStockIssuanceCosts_019fc884-1c1d-7543-9831-e656ff01e259" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019fc884-1c1d-7a10-876a-2858b06862b7" 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_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019fc884-1c1d-7a10-876a-2858b06862b7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019fc884-1c1d-71f4-8649-a3d8ec6bcb9b" 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_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019fc884-1c1d-71f4-8649-a3d8ec6bcb9b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fc884-1c1d-7980-b18d-fbab7184a7f5" 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_EquityAbstract_019fc884-1c1d-74b0-84ad-6edd4fcc9b42" xlink:to="loc_us-gaap_StockholdersEquity_019fc884-1c1d-7980-b18d-fbab7184a7f5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019fc884-1c1d-7a55-8397-bce5b0528554" 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_StatementLineItems_019fc884-1c1d-7832-8dd3-1fca7824e018" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019fc884-1c1d-7a55-8397-bce5b0528554" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="ida-20260930.xsd#IdahoPowerCompanyConsolidatedStatementsofCashFlows"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/IdahoPowerCompanyConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-7026-a951-3266774a103b" 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_019fc884-1c1d-7383-858c-992881ca1770" 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_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-7383-858c-992881ca1770" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-77f0-a0e6-dd89ca29182c" 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_019fc884-1c1d-7383-858c-992881ca1770" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-77f0-a0e6-dd89ca29182c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-77f0-a0e6-dd89ca29182c_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_019fc884-1c1d-77f0-a0e6-dd89ca29182c" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-77f0-a0e6-dd89ca29182c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-71c6-b27f-dda9bfde4156" 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_019fc884-1c1d-77f0-a0e6-dd89ca29182c" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-71c6-b27f-dda9bfde4156" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7d8f-9ac1-452621d8eac0" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-71c6-b27f-dda9bfde4156" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7d8f-9ac1-452621d8eac0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019fc884-1c1d-7cc7-ad32-aed2a58404d8" 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_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_ProfitLoss_019fc884-1c1d-7cc7-ad32-aed2a58404d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" 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_StatementLineItems_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019fc884-1c1d-7649-aefd-55bdf6f269ad" 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_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019fc884-1c1d-7649-aefd-55bdf6f269ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019fc884-1c1d-7347-b793-2cabf97e3d37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019fc884-1c1d-7347-b793-2cabf97e3d37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRegulatoryAssetsAndLiabilities_019fc884-1c1d-70f2-8c78-91622eb207d4" 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_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_IncreaseDecreaseInRegulatoryAssetsAndLiabilities_019fc884-1c1d-70f2-8c78-91622eb207d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019fc884-1c1d-7b61-ada5-bcba2b10f771" 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_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_019fc884-1c1d-7b61-ada5-bcba2b10f771" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitContributions_019fc884-1c1d-704b-95f1-b6832a8936fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionAndOtherPostretirementBenefitContributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_PensionAndOtherPostretirementBenefitContributions_019fc884-1c1d-704b-95f1-b6832a8936fe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019fc884-1c1d-7ecb-b140-5edecd30e9ab" 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_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019fc884-1c1d-7ecb-b140-5edecd30e9ab" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_019fc884-1c1d-70da-8df1-c2ef0b98c92d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_019fc884-1c1d-70da-8df1-c2ef0b98c92d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions_019fc884-1c1d-7814-9dd3-a87a435ba027" 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_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions_019fc884-1c1d-7814-9dd3-a87a435ba027" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_019fc884-1c1d-732f-8c0d-9f13d3706faf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNoncashIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019fc884-1c1d-74e4-961f-25a4a62d1473" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_019fc884-1c1d-732f-8c0d-9f13d3706faf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" 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_StatementLineItems_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_019fc884-1c1d-7a41-a4d6-bf6416555113" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_019fc884-1c1d-7a41-a4d6-bf6416555113" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_019fc884-1c1d-7606-b0ea-7115fcc9f8ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_019fc884-1c1d-7606-b0ea-7115fcc9f8ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInMaterialsAndSupplies_019fc884-1c1d-7da7-88b9-81a1841a441e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInMaterialsAndSupplies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_IncreaseDecreaseInMaterialsAndSupplies_019fc884-1c1d-7da7-88b9-81a1841a441e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019fc884-1c1d-793e-adc4-140ad36f3710" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019fc884-1c1d-793e-adc4-140ad36f3710" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_019fc884-1c1d-7488-b9f1-d6752787c72b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_019fc884-1c1d-7488-b9f1-d6752787c72b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_019fc884-1c1d-7996-b325-86c5e0271aa0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_019fc884-1c1d-7996-b325-86c5e0271aa0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019fc884-1c1d-7884-ad62-d17b9aa58349" 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_IncreaseDecreaseInOperatingCapitalAbstract_019fc884-1c1d-73f5-8536-97265549b92d" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019fc884-1c1d-7884-ad62-d17b9aa58349" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019fc884-1c1d-717d-bc3f-649b4f8e2f54" 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_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019fc884-1c1d-717d-bc3f-649b4f8e2f54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019fc884-1c1d-7405-bfc1-6540647ff57d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019fc884-1c1d-717d-bc3f-649b4f8e2f54" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019fc884-1c1d-7405-bfc1-6540647ff57d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfOtherProductiveAssets_019fc884-1c1d-7bc1-9d1c-0abfd564e114" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfOtherProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019fc884-1c1d-717d-bc3f-649b4f8e2f54" xlink:to="loc_us-gaap_ProceedsFromSaleOfOtherProductiveAssets_019fc884-1c1d-7bc1-9d1c-0abfd564e114" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfIntangibleAssets_019fc884-1c1d-7b1d-a352-907aaa99d291" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019fc884-1c1d-717d-bc3f-649b4f8e2f54" xlink:to="loc_us-gaap_ProceedsFromSaleOfIntangibleAssets_019fc884-1c1d-7b1d-a352-907aaa99d291" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_019fc884-1c1d-7185-a405-dff257265c57" 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_019fc884-1c1d-717d-bc3f-649b4f8e2f54" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_019fc884-1c1d-7185-a405-dff257265c57" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019fc884-1c1d-7683-8e88-e004391cb685" 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_019fc884-1c1d-717d-bc3f-649b4f8e2f54" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019fc884-1c1d-7683-8e88-e004391cb685" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" 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_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019fc884-1c1d-7037-b13e-21eb0c5e9d42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019fc884-1c1d-7037-b13e-21eb0c5e9d42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PremiumDiscountOnIssuanceOfLongTermDebt_019fc884-1c1d-742c-b8be-46f3857bd3ca" xlink:href="ida-20260930.xsd#ida_PremiumDiscountOnIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_ida_PremiumDiscountOnIssuanceOfLongTermDebt_019fc884-1c1d-742c-b8be-46f3857bd3ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_019fc884-1c1d-7c81-88dd-996a3809730a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_019fc884-1c1d-7c81-88dd-996a3809730a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_019fc884-1c1d-7060-9685-9b1db9afbf46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_019fc884-1c1d-7060-9685-9b1db9afbf46" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_019fc884-1c1d-7c49-ad55-c417e32ce889" 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_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_019fc884-1c1d-7c49-ad55-c417e32ce889" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019fc884-1c1d-751b-82dc-cce91254fc3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019fc884-1c1d-751b-82dc-cce91254fc3b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromContributionsFromParent_019fc884-1c1d-7777-afb3-72dd0f06f804" 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_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_ProceedsFromContributionsFromParent_019fc884-1c1d-7777-afb3-72dd0f06f804" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019fc884-1c1d-7055-8575-6ae36b8122f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019fc884-1c1d-7055-8575-6ae36b8122f3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019fc884-1c1d-7f90-806b-049577a9d51c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019fc884-1c1d-7f90-806b-049577a9d51c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019fc884-1c1d-7f11-904c-b7624752df0b" 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_019fc884-1c1d-78e5-b222-0b9e8b24799f" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019fc884-1c1d-7f11-904c-b7624752df0b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019fc884-1c1d-7c25-80d3-1987e9ff1814" 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_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019fc884-1c1d-7c25-80d3-1987e9ff1814" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019fc884-1c1d-7a45-b589-87b696f01e83" 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_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019fc884-1c1d-7a45-b589-87b696f01e83" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019fc884-1c1d-71f3-8f9c-acb4e2d2e940" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_019fc884-1c1d-7579-94e9-afcd3709518f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_019fc884-1c1d-7579-94e9-afcd3709518f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_019fc884-1c1d-74fb-8f4c-a3b114361481" 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_SupplementalCashFlowInformationAbstract_019fc884-1c1d-7579-94e9-afcd3709518f" xlink:to="loc_us-gaap_InterestPaidNet_019fc884-1c1d-74fb-8f4c-a3b114361481" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019fc884-1c1d-7a3a-8d59-d5076565d96e" 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_StatementLineItems_019fc884-1c1d-7026-a951-3266774a103b" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019fc884-1c1d-7a3a-8d59-d5076565d96e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_019fc884-1c1d-71a1-b5b2-119fd8fa0902" 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_019fc884-1c1d-7a3a-8d59-d5076565d96e" xlink:to="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_019fc884-1c1d-71a1-b5b2-119fd8fa0902" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_019fc884-1c1d-7ce3-985f-dad0d372ca88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_019fc884-1c1d-7a3a-8d59-d5076565d96e" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_019fc884-1c1d-7ce3-985f-dad0d372ca88" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/IdahoPowerCompanyStatementofComprehensiveIncomeParenthetical" xlink:type="simple" xlink:href="ida-20260930.xsd#IdahoPowerCompanyStatementofComprehensiveIncomeParenthetical"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/IdahoPowerCompanyStatementofComprehensiveIncomeParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-7974-b432-5dabf10145f5" 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_019fc884-1c1d-7438-b7bd-17bdcd241fe2" 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_019fc884-1c1d-7974-b432-5dabf10145f5" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-7438-b7bd-17bdcd241fe2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-79a3-9cb5-0d188f9c10ad" 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_019fc884-1c1d-7438-b7bd-17bdcd241fe2" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-79a3-9cb5-0d188f9c10ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-79a3-9cb5-0d188f9c10ad_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_019fc884-1c1d-79a3-9cb5-0d188f9c10ad" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-79a3-9cb5-0d188f9c10ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7ac8-8973-9544b4a42d38" 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_019fc884-1c1d-79a3-9cb5-0d188f9c10ad" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7ac8-8973-9544b4a42d38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7444-a8a3-6497e2df584c" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-7ac8-8973-9544b4a42d38" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7444-a8a3-6497e2df584c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax_019fc884-1c1d-7a34-9c79-2c8a6ebf9016" 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_019fc884-1c1d-7974-b432-5dabf10145f5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax_019fc884-1c1d-7a34-9c79-2c8a6ebf9016" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/IdahoPowercompanyConsolidatedBalanceSheetParenthetical" xlink:type="simple" xlink:href="ida-20260930.xsd#IdahoPowercompanyConsolidatedBalanceSheetParenthetical"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/IdahoPowercompanyConsolidatedBalanceSheetParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fc884-1c1d-793e-b198-30e1a6f3f26d" 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_019fc884-1c1d-7163-a88e-904a871e678d" 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_019fc884-1c1d-793e-b198-30e1a6f3f26d" xlink:to="loc_us-gaap_StatementTable_019fc884-1c1d-7163-a88e-904a871e678d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-736e-bf8d-9a60b7fb747d" 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_019fc884-1c1d-7163-a88e-904a871e678d" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-736e-bf8d-9a60b7fb747d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-736e-bf8d-9a60b7fb747d_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_019fc884-1c1d-736e-bf8d-9a60b7fb747d" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-736e-bf8d-9a60b7fb747d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7b21-9025-eb06770491c9" 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_019fc884-1c1d-736e-bf8d-9a60b7fb747d" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7b21-9025-eb06770491c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7e9e-823e-32d6d33e2ea9" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-7b21-9025-eb06770491c9" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-7e9e-823e-32d6d33e2ea9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019fc884-1c1d-713b-a254-b574b3ec4075" 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_StatementLineItems_019fc884-1c1d-793e-b198-30e1a6f3f26d" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019fc884-1c1d-713b-a254-b574b3ec4075" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulOtherReceivablesCurrent_019fc884-1c1d-79bf-a797-46703af06b80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForDoubtfulOtherReceivablesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-793e-b198-30e1a6f3f26d" xlink:to="loc_us-gaap_AllowanceForDoubtfulOtherReceivablesCurrent_019fc884-1c1d-79bf-a797-46703af06b80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019fc884-1c1d-7ee9-ae09-1f1e8ab75554" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-793e-b198-30e1a6f3f26d" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019fc884-1c1d-7ee9-ae09-1f1e8ab75554" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_019fc884-1c1d-787a-8e08-aaf1eff094c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fc884-1c1d-793e-b198-30e1a6f3f26d" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_019fc884-1c1d-787a-8e08-aaf1eff094c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019fc884-1c1d-7636-89d9-219b01d6a0eb" 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_StatementLineItems_019fc884-1c1d-793e-b198-30e1a6f3f26d" xlink:to="loc_us-gaap_CommonStockSharesIssued_019fc884-1c1d-7636-89d9-219b01d6a0eb" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/INCOMETAXESLevel4Details" xlink:type="simple" xlink:href="ida-20260930.xsd#INCOMETAXESLevel4Details"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/INCOMETAXESLevel4Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:href="ida-20260930.xsd#ida_IncomeTaxExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IncomeTaxExpenseTable_019fc884-1c1d-7b37-9a85-b517c6ca6ed0" xlink:href="ida-20260930.xsd#ida_IncomeTaxExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_ida_IncomeTaxExpenseTable_019fc884-1c1d-7b37-9a85-b517c6ca6ed0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1c1d-761b-ae34-a669bcaccc8c" 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_ida_IncomeTaxExpenseTable_019fc884-1c1d-7b37-9a85-b517c6ca6ed0" xlink:to="loc_dei_LegalEntityAxis_019fc884-1c1d-761b-ae34-a669bcaccc8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-761b-ae34-a669bcaccc8c_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_019fc884-1c1d-761b-ae34-a669bcaccc8c" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-761b-ae34-a669bcaccc8c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1c1d-7ab7-9ed1-f35edd713f16" 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_019fc884-1c1d-761b-ae34-a669bcaccc8c" xlink:to="loc_dei_EntityDomain_019fc884-1c1d-7ab7-9ed1-f35edd713f16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-72fa-bcc9-557aeabeb411" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1c1d-7ab7-9ed1-f35edd713f16" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1c1d-72fa-bcc9-557aeabeb411" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_019fc884-1cc8-78ae-b06d-dd84dd7494bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_019fc884-1cc8-78ae-b06d-dd84dd7494bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_019fc884-1cc8-73a4-b77d-84f48338f7c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_019fc884-1cc8-73a4-b77d-84f48338f7c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationPriorYearIncomeTaxes_01a159df-b362-710a-bcb9-796ad6fdcd77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationPriorYearIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_IncomeTaxReconciliationPriorYearIncomeTaxes_01a159df-b362-710a-bcb9-796ad6fdcd77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_019fc884-1cc8-7dd2-8585-20d98319c143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_019fc884-1cc8-7dd2-8585-20d98319c143" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IncomeTaxExpenseBeforeAdditionalADITCAmortization_019fc884-1cc8-750e-b7dc-7abc9a198adf" xlink:href="ida-20260930.xsd#ida_IncomeTaxExpenseBeforeAdditionalADITCAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_ida_IncomeTaxExpenseBeforeAdditionalADITCAmortization_019fc884-1cc8-750e-b7dc-7abc9a198adf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherReconcilingItems_019fc884-1cc8-72ca-b777-049d0405243d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationOtherReconcilingItems"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherReconcilingItems_019fc884-1cc8-72ca-b777-049d0405243d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019fc884-1cc8-7630-a4f7-b3be1fdd2207" 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_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019fc884-1cc8-7630-a4f7-b3be1fdd2207" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019fc884-1cc8-72cc-abcb-5f8a695c83b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019fc884-1cc8-72cc-abcb-5f8a695c83b5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxJurisdictionOfDomicileExtensibleEnumeration_019fc884-1cc8-748a-a2de-d42a4f17c0e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxJurisdictionOfDomicileExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7af3-a406-0768f42fa42b" xlink:to="loc_us-gaap_TaxJurisdictionOfDomicileExtensibleEnumeration_019fc884-1cc8-748a-a2de-d42a4f17c0e3" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/INCOMETAXESSupplementalDisclosuresDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#INCOMETAXESSupplementalDisclosuresDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/INCOMETAXESSupplementalDisclosuresDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7c19-9d62-9e9dfd4a8fd2" xlink:href="ida-20260930.xsd#ida_IncomeTaxExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IncomeTaxExpenseTable_019fc884-1cc8-77e8-9de1-4bf4e3fd967f" xlink:href="ida-20260930.xsd#ida_IncomeTaxExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7c19-9d62-9e9dfd4a8fd2" xlink:to="loc_ida_IncomeTaxExpenseTable_019fc884-1cc8-77e8-9de1-4bf4e3fd967f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-775e-94a8-549a51d3e896" 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_ida_IncomeTaxExpenseTable_019fc884-1cc8-77e8-9de1-4bf4e3fd967f" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-775e-94a8-549a51d3e896" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-775e-94a8-549a51d3e896_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_019fc884-1cc8-775e-94a8-549a51d3e896" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-775e-94a8-549a51d3e896_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-70bb-aaeb-0b28416500de" 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_019fc884-1cc8-775e-94a8-549a51d3e896" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-70bb-aaeb-0b28416500de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7117-ab55-1a7aed5ef0a2" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-70bb-aaeb-0b28416500de" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7117-ab55-1a7aed5ef0a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIncomeTaxRefunds_019fc884-1cc8-7d47-9d27-0e5a1ee08ebd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIncomeTaxRefunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7c19-9d62-9e9dfd4a8fd2" xlink:to="loc_us-gaap_ProceedsFromIncomeTaxRefunds_019fc884-1cc8-7d47-9d27-0e5a1ee08ebd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019fc884-1cc8-7dd7-8e06-43d1fdb52ff4" 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_ida_IncomeTaxExpenseLineItems_019fc884-1cc8-7c19-9d62-9e9dfd4a8fd2" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019fc884-1cc8-7dd7-8e06-43d1fdb52ff4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details" xlink:type="simple" xlink:href="ida-20260930.xsd#REGULATORYMATTERSLevel4Details"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:href="ida-20260930.xsd#ida_RateCaseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesByJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:to="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" 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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" 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_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:href="ida-20260930.xsd#ida_RateCaseMatterAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:href="ida-20260930.xsd#ida_HellsCanyonComplexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:href="ida-20260930.xsd#ida_RateCasesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:href="ida-20260930.xsd#ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:href="ida-20260930.xsd#ida_IdahoFixedCostAdjustmentNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:href="ida-20260930.xsd#ida_A2023SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:href="ida-20260930.xsd#ida_OregonPowerCostAdjustmentWildfireMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:href="ida-20260930.xsd#ida_A2025RateCaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:href="ida-20260930.xsd#ida_October2025SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fc884-1cc8-7695-8665-0c9fa1c01540" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fc884-1cc8-7695-8665-0c9fa1c01540" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fc884-1cc8-778b-9011-74fe49945e5e" 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_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fc884-1cc8-778b-9011-74fe49945e5e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" 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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:href="ida-20260930.xsd#ida_ADITCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:to="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" 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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:to="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:href="ida-20260930.xsd#ida_RequestedYearAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:href="ida-20260930.xsd#ida_A2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:to="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" 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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" 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_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:to="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" 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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:href="ida-20260930.xsd#ida_AuthorizedReturnOnEquityInRateCaseMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:href="ida-20260930.xsd#ida_PercentageCapOnFcaAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:href="ida-20260930.xsd#ida_Annualfixedcostadjustmentmechanismdeferral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:href="ida-20260930.xsd#ida_InvestmentTaxCreditsRemainsAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:href="ida-20260930.xsd#ida_PublicUtilitiesAnnualAmortizationCapValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details_1" xlink:type="simple" xlink:href="ida-20260930.xsd#REGULATORYMATTERSLevel4Details_1"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:href="ida-20260930.xsd#ida_RateCaseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesByJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:to="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" 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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" 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_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:href="ida-20260930.xsd#ida_RateCaseMatterAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:href="ida-20260930.xsd#ida_HellsCanyonComplexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:href="ida-20260930.xsd#ida_RateCasesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:href="ida-20260930.xsd#ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:href="ida-20260930.xsd#ida_IdahoFixedCostAdjustmentNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:href="ida-20260930.xsd#ida_A2023SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:href="ida-20260930.xsd#ida_OregonPowerCostAdjustmentWildfireMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:href="ida-20260930.xsd#ida_A2025RateCaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:href="ida-20260930.xsd#ida_October2025SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" 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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:href="ida-20260930.xsd#ida_ADITCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:to="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" 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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:to="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:href="ida-20260930.xsd#ida_RequestedYearAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:href="ida-20260930.xsd#ida_A2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:to="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" 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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" 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_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:to="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" 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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:href="ida-20260930.xsd#ida_AuthorizedReturnOnEquityInRateCaseMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:href="ida-20260930.xsd#ida_PercentageCapOnFcaAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:href="ida-20260930.xsd#ida_Annualfixedcostadjustmentmechanismdeferral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:href="ida-20260930.xsd#ida_InvestmentTaxCreditsRemainsAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:href="ida-20260930.xsd#ida_PublicUtilitiesAnnualAmortizationCapValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details_2" xlink:type="simple" xlink:href="ida-20260930.xsd#REGULATORYMATTERSLevel4Details_2"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:href="ida-20260930.xsd#ida_RateCaseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesByJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:to="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" 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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" 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_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:href="ida-20260930.xsd#ida_RateCaseMatterAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:href="ida-20260930.xsd#ida_HellsCanyonComplexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:href="ida-20260930.xsd#ida_RateCasesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:href="ida-20260930.xsd#ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:href="ida-20260930.xsd#ida_IdahoFixedCostAdjustmentNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:href="ida-20260930.xsd#ida_A2023SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:href="ida-20260930.xsd#ida_OregonPowerCostAdjustmentWildfireMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:href="ida-20260930.xsd#ida_A2025RateCaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:href="ida-20260930.xsd#ida_October2025SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" 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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:href="ida-20260930.xsd#ida_ADITCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:to="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" 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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:to="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:href="ida-20260930.xsd#ida_RequestedYearAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:href="ida-20260930.xsd#ida_A2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:to="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" 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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" 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_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:to="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" 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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fc884-1cc8-778b-9011-74fe49945e5e" 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_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fc884-1cc8-778b-9011-74fe49945e5e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:href="ida-20260930.xsd#ida_AuthorizedReturnOnEquityInRateCaseMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:href="ida-20260930.xsd#ida_PercentageCapOnFcaAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:href="ida-20260930.xsd#ida_Annualfixedcostadjustmentmechanismdeferral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:href="ida-20260930.xsd#ida_InvestmentTaxCreditsRemainsAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:href="ida-20260930.xsd#ida_PublicUtilitiesAnnualAmortizationCapValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details_3" xlink:type="simple" xlink:href="ida-20260930.xsd#REGULATORYMATTERSLevel4Details_3"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/REGULATORYMATTERSLevel4Details_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:href="ida-20260930.xsd#ida_RateCaseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727e-b1d5-8558bc1dfa82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727e-b1d5-8558bc1dfa82" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_stpr_ID_019fc884-1cc8-7625-8434-5b3597e6d9f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-789b-b407-f730cd2417f3" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7418-9f75-6d076e1d51bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesByJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-79af-a2f6-5435a536bf3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_019fc884-1cc8-79af-a2f6-5435a536bf3c" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_019fc884-1cc8-7c0b-a687-a1f142d267d9" xlink:to="loc_stpr_ID_019fc884-1cc8-7bca-a340-f5da58437437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-70b1-9ce6-5624b48f167b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" 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_019fc884-1cc8-70b1-9ce6-5624b48f167b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" 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_019fc884-1cc8-7ad1-b34f-8eade1da82fe" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-791a-99af-e9ebeeaebec5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:href="ida-20260930.xsd#ida_RateCaseMatterAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7ed2-ad90-051b0fb91cf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:href="ida-20260930.xsd#ida_RateCaseMatterDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCaseMatterAxis_019fc884-1cc8-7ed2-ad90-051b0fb91cf6" xlink:to="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanCostsMember_019fc884-1cc8-7f1e-aae6-e8b5d90256b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:href="ida-20260930.xsd#ida_HellsCanyonComplexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7439-b448-caabc223b597" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-70e8-95d7-ae3a20523e0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:href="ida-20260930.xsd#ida_WildfireMitigationPlanDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseMatterDomain_019fc884-1cc8-7e86-acb8-a4dbca47c4b8" xlink:to="loc_ida_WildfireMitigationPlanDeferralMember_019fc884-1cc8-7b59-9bbf-38933180d74b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:href="ida-20260930.xsd#ida_RateCasesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-75d2-9bdf-acc4b85e4abd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-75d2-9bdf-acc4b85e4abd" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:href="ida-20260930.xsd#ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_SettlementStipulationInvestmentTaxCreditsAndIdahoSharingMechanismMember_019fc884-1cc8-713f-a26e-ba736793ff8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc8-787b-822a-db5752459349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:href="ida-20260930.xsd#ida_IdahoFixedCostAdjustmentNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7d16-8596-94be294bb388" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc8-7942-997c-c2318de79dc1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-792b-ac3b-f77efa793188" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:href="ida-20260930.xsd#ida_A2023SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2023SettlementStipulationMember_019fc884-1cc8-7c58-9aaa-dc9db7420e3a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:href="ida-20260930.xsd#ida_OregonPowerCostAdjustmentWildfireMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_OregonPowerCostAdjustmentWildfireMember_019fc884-1cc8-7846-ab72-ab28892d61a1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:href="ida-20260930.xsd#ida_A2025RateCaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_A2025RateCaseMember_019fc884-1cc8-77f3-82fb-505f9fd4c3b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:href="ida-20260930.xsd#ida_October2025SettlementStipulationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-796b-95a6-a7258a9db9e2" xlink:to="loc_ida_October2025SettlementStipulationMember_019fc884-1cc8-74d4-83fd-f674e8592a2d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingAxis_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" 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_019fc884-1cc8-7cc6-a830-e51a0a1cf3ac" xlink:to="loc_us-gaap_PublicUtilitiesRegulatoryProceedingDomain_019fc884-1cc8-71a7-abd5-da5b3968476f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-7dc7-a236-22f9dc238e4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:href="ida-20260930.xsd#ida_AvailabilityFutureUseDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_AvailabilityFutureUseAxis_019fc884-1cc8-7dc7-a236-22f9dc238e4f" xlink:to="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:href="ida-20260930.xsd#ida_ADITCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_AvailabilityFutureUseDomain_019fc884-1cc8-71b3-a1fa-5d8bfcedfcb9" xlink:to="loc_ida_ADITCMember_019fc884-1cc8-7929-b34c-9c02bdb16e80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7c75-b1ca-61ba99d3fde4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" 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_019fc884-1cc8-7c75-b1ca-61ba99d3fde4" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_ID"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_019fc884-1cc8-7bc9-82a7-a97e8188a37f" xlink:to="loc_stpr_ID_019fc884-1cc8-7e51-81f2-fc90d3d01129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:href="ida-20260930.xsd#ida_RequestedYearAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-74d0-a0ab-10e8608c4e63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:href="ida-20260930.xsd#ida_RequestedYearDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RequestedYearAxis_019fc884-1cc8-74d0-a0ab-10e8608c4e63" xlink:to="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:href="ida-20260930.xsd#ida_A2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RequestedYearDomain_019fc884-1cc8-7413-8596-17381632b435" xlink:to="loc_ida_A2025Member_019fc884-1cc8-74ab-8311-886e8a8d5250" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_srt_StatementScenarioAxis_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-7fb0-b888-85450a721d85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" 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_019fc884-1cc8-7fb0-b888-85450a721d85" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" 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_019fc884-1cc8-78d8-889e-d3a355b7302f" xlink:to="loc_srt_ScenarioForecastMember_019fc884-1cc8-7278-9833-9c9e73a4802c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" 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_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-796e-9324-bd1c679c4401_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" 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_019fc884-1cc8-796e-9324-bd1c679c4401" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7aa8-b271-854ff65fe6cf" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-78b6-a5c5-ee05f4c77965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fc884-1cc8-7695-8665-0c9fa1c01540" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryAssetsTable_019fc884-1cc8-7400-be8e-6d69d044697e" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fc884-1cc8-7695-8665-0c9fa1c01540" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:href="ida-20260930.xsd#ida_AuthorizedReturnOnEquityInRateCaseMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_AuthorizedReturnOnEquityInRateCaseMinimum_019fc884-1cc8-70ba-90c6-97696295b003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:href="ida-20260930.xsd#ida_PercentageCapOnFcaAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PercentageCapOnFcaAdjustment_019fc884-1cc8-7ca7-b0b0-43ed16fa8044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:href="ida-20260930.xsd#ida_Annualfixedcostadjustmentmechanismdeferral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_Annualfixedcostadjustmentmechanismdeferral_019fc884-1cc8-7df6-a5f6-f2c0d2857c57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:href="ida-20260930.xsd#ida_InvestmentTaxCreditsRemainsAvailable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_InvestmentTaxCreditsRemainsAvailable_019fc884-1cc8-78cb-a2b6-26cb4d59016d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount_019fc884-1cc8-741e-ace3-14fa11ba1a1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:href="ida-20260930.xsd#ida_PublicUtilitiesAnnualAmortizationCapValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_ida_PublicUtilitiesAnnualAmortizationCapValue_019fc884-1cc8-7af5-8afc-7f341174b556" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsInvestment_019fc884-1cc8-7e27-a1fa-84124854e46d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_RegulatoryAssets_019fc884-1cc8-7e61-9812-085c0d2646cf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" 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_ida_RateCaseLineItems_019fc884-1cc8-726d-a439-7d62f30bd397" xlink:to="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_019fc884-1cc8-7d92-b3d9-55e3a27a9268" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/REVENUESDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#REVENUESDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/REVENUESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019fc884-1cc8-7c47-b622-b30545ede2b6" 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_019fc884-1cc8-7624-9fa0-a038192f4c1b" 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_019fc884-1cc8-7c47-b622-b30545ede2b6" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetAxis_019fc884-1cc8-7a27-a03d-c9a5c47325a6" 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_DisaggregationOfRevenueTable_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_us-gaap_RegulatoryAssetAxis_019fc884-1cc8-7a27-a03d-c9a5c47325a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_019fc884-1cc8-7a27-a03d-c9a5c47325a6_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_019fc884-1cc8-7a27-a03d-c9a5c47325a6" xlink:to="loc_us-gaap_RegulatoryAssetDomain_019fc884-1cc8-7a27-a03d-c9a5c47325a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_019fc884-1cc8-7958-9d94-5626a525ab1c" 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_019fc884-1cc8-7a27-a03d-c9a5c47325a6" xlink:to="loc_us-gaap_RegulatoryAssetDomain_019fc884-1cc8-7958-9d94-5626a525ab1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityAxis_019fc884-1cc8-7be9-9590-b393bc2f5fab" 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_DisaggregationOfRevenueTable_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_us-gaap_RegulatoryLiabilityAxis_019fc884-1cc8-7be9-9590-b393bc2f5fab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityDomain_019fc884-1cc8-7be9-9590-b393bc2f5fab_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_019fc884-1cc8-7be9-9590-b393bc2f5fab" xlink:to="loc_us-gaap_RegulatoryLiabilityDomain_019fc884-1cc8-7be9-9590-b393bc2f5fab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityDomain_019fc884-1cc8-7d31-b39e-c1abd441972a" 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_019fc884-1cc8-7be9-9590-b393bc2f5fab" xlink:to="loc_us-gaap_RegulatoryLiabilityDomain_019fc884-1cc8-7d31-b39e-c1abd441972a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IPUCauthorizedAFUDCCollectionHCCRelicensingGrossMember_019fc884-1cc8-7591-a259-b98f491691bb" xlink:href="ida-20260930.xsd#ida_IPUCauthorizedAFUDCCollectionHCCRelicensingGrossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_019fc884-1cc8-7d31-b39e-c1abd441972a" xlink:to="loc_ida_IPUCauthorizedAFUDCCollectionHCCRelicensingGrossMember_019fc884-1cc8-7591-a259-b98f491691bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-79ef-bfd1-eb903761b433" 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_DisaggregationOfRevenueTable_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-79ef-bfd1-eb903761b433" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-79ef-bfd1-eb903761b433_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_019fc884-1cc8-79ef-bfd1-eb903761b433" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-79ef-bfd1-eb903761b433_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-71ce-a2b8-7c5ca98cf90c" 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_019fc884-1cc8-79ef-bfd1-eb903761b433" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-71ce-a2b8-7c5ca98cf90c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-72e0-be2c-b83e5c1eb368" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-71ce-a2b8-7c5ca98cf90c" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-72e0-be2c-b83e5c1eb368" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019fc884-1cc8-7cd6-9e48-2994a507fff4" 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_DisaggregationOfRevenueTable_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019fc884-1cc8-7cd6-9e48-2994a507fff4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fc884-1cc8-7cd6-9e48-2994a507fff4_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_019fc884-1cc8-7cd6-9e48-2994a507fff4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fc884-1cc8-7cd6-9e48-2994a507fff4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fc884-1cc8-77fc-bc1d-d99f47f017be" 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_019fc884-1cc8-7cd6-9e48-2994a507fff4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fc884-1cc8-77fc-bc1d-d99f47f017be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7c8a-a910-d760b65a8ab3" xlink:href="ida-20260930.xsd#ida_HellsCanyonComplexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fc884-1cc8-77fc-bc1d-d99f47f017be" xlink:to="loc_ida_HellsCanyonComplexMember_019fc884-1cc8-7c8a-a910-d760b65a8ab3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesAxis_019fc884-1cc8-7e98-8fdb-50666067edad" xlink:href="ida-20260930.xsd#ida_RateCasesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_ida_RateCasesAxis_019fc884-1cc8-7e98-8fdb-50666067edad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-7e98-8fdb-50666067edad_default" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-7e98-8fdb-50666067edad" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-7e98-8fdb-50666067edad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc8-7544-b2ef-0a36352afc0a" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc8-7e98-8fdb-50666067edad" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc8-7544-b2ef-0a36352afc0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7ed4-947e-ddbd730e17df" xlink:href="ida-20260930.xsd#ida_IdahoFixedCostAdjustmentNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc8-7544-b2ef-0a36352afc0a" xlink:to="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-7ed4-947e-ddbd730e17df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019fc884-1cc8-7e55-a6a0-90b78279ca16" 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_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_srt_MajorCustomersAxis_019fc884-1cc8-7e55-a6a0-90b78279ca16" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7e55-a6a0-90b78279ca16_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_019fc884-1cc8-7e55-a6a0-90b78279ca16" xlink:to="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7e55-a6a0-90b78279ca16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" 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_019fc884-1cc8-7e55-a6a0-90b78279ca16" xlink:to="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ResidentialRetailRevenueMember_019fc884-1cc8-74ce-b542-7f315a7f3054" xlink:href="ida-20260930.xsd#ida_ResidentialRetailRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" xlink:to="loc_ida_ResidentialRetailRevenueMember_019fc884-1cc8-74ce-b542-7f315a7f3054" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CommercialRetailRevenueMember_019fc884-1cc8-73eb-8abb-91f284ac1c7b" xlink:href="ida-20260930.xsd#ida_CommercialRetailRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" xlink:to="loc_ida_CommercialRetailRevenueMember_019fc884-1cc8-73eb-8abb-91f284ac1c7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IndustrialRetailRevenueMember_019fc884-1cc8-735d-a261-8529695ad3d6" xlink:href="ida-20260930.xsd#ida_IndustrialRetailRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" xlink:to="loc_ida_IndustrialRetailRevenueMember_019fc884-1cc8-735d-a261-8529695ad3d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IrrigationRetailRevenueMember_019fc884-1cc8-7c64-8601-8789664bc57a" xlink:href="ida-20260930.xsd#ida_IrrigationRetailRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" xlink:to="loc_ida_IrrigationRetailRevenueMember_019fc884-1cc8-7c64-8601-8789664bc57a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DeferredRevenueAfudcMember_019fc884-1cc8-7733-8090-ae7eb28c6b60" xlink:href="ida-20260930.xsd#ida_DeferredRevenueAfudcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019fc884-1cc8-7b0f-819e-19ece962291a" xlink:to="loc_ida_DeferredRevenueAfudcMember_019fc884-1cc8-7733-8090-ae7eb28c6b60" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fc884-1cc8-75b0-97ec-72f5ad38eb1f" 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_019fc884-1cc8-7624-9fa0-a038192f4c1b" xlink:to="loc_srt_ProductOrServiceAxis_019fc884-1cc8-75b0-97ec-72f5ad38eb1f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-75b0-97ec-72f5ad38eb1f_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_019fc884-1cc8-75b0-97ec-72f5ad38eb1f" xlink:to="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-75b0-97ec-72f5ad38eb1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" 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_019fc884-1cc8-75b0-97ec-72f5ad38eb1f" xlink:to="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RetailrevenuesMember_019fc884-1cc8-72a2-9d37-6ccf6517c60b" xlink:href="ida-20260930.xsd#ida_RetailrevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_RetailrevenuesMember_019fc884-1cc8-72a2-9d37-6ccf6517c60b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-76d5-8e6d-e172611cd3ed" xlink:href="ida-20260930.xsd#ida_IdahoFixedCostAdjustmentNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_IdahoFixedCostAdjustmentNettingMember_019fc884-1cc8-76d5-8e6d-e172611cd3ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_WholesaleenergysalesMember_019fc884-1cc8-78b0-a357-ed8aad756821" xlink:href="ida-20260930.xsd#ida_WholesaleenergysalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_WholesaleenergysalesMember_019fc884-1cc8-78b0-a357-ed8aad756821" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_TransmissionserviceswheelingMember_019fc884-1cc8-75de-a548-1dda4bfb5c93" xlink:href="ida-20260930.xsd#ida_TransmissionserviceswheelingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_TransmissionserviceswheelingMember_019fc884-1cc8-75de-a548-1dda4bfb5c93" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_EnergyefficiencyprogramrevenuesMember_019fc884-1cc8-7020-91ac-5afededd25a6" xlink:href="ida-20260930.xsd#ida_EnergyefficiencyprogramrevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_EnergyefficiencyprogramrevenuesMember_019fc884-1cc8-7020-91ac-5afededd25a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OtherrevenuesMember_019fc884-1cc8-72ae-870a-8cdcce193ab1" xlink:href="ida-20260930.xsd#ida_OtherrevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_OtherrevenuesMember_019fc884-1cc8-72ae-870a-8cdcce193ab1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DerivativeRevenuesNettingMember_019fc884-1cc8-7f7d-aa95-63564949a0e2" xlink:href="ida-20260930.xsd#ida_DerivativeRevenuesNettingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fc884-1cc8-741d-b69e-ce8d7dd50b62" xlink:to="loc_ida_DerivativeRevenuesNettingMember_019fc884-1cc8-7f7d-aa95-63564949a0e2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fc884-1cc8-725a-8c02-0a18ec27ca38" 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_019fc884-1cc8-7c47-b622-b30545ede2b6" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fc884-1cc8-725a-8c02-0a18ec27ca38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilities_019fc884-1cc8-7c69-aa83-af004a507eb1" 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_DisaggregationOfRevenueLineItems_019fc884-1cc8-7c47-b622-b30545ede2b6" xlink:to="loc_us-gaap_RegulatoryLiabilities_019fc884-1cc8-7c69-aa83-af004a507eb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatedOperatingRevenueExpenseOtherNet_019fc884-1cc8-7559-aa6d-601ad99a7340" xlink:href="ida-20260930.xsd#ida_RegulatedOperatingRevenueExpenseOtherNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019fc884-1cc8-7c47-b622-b30545ede2b6" xlink:to="loc_ida_RegulatedOperatingRevenueExpenseOtherNet_019fc884-1cc8-7559-aa6d-601ad99a7340" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/LONGTERMDEBTDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#LONGTERMDEBTDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/LONGTERMDEBTDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" 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_019fc884-1cc8-7223-b1eb-63f80b3b313c" 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_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_us-gaap_DebtInstrumentTable_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-77e6-8cb4-31b56184ad19" 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_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-77e6-8cb4-31b56184ad19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-77e6-8cb4-31b56184ad19_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_019fc884-1cc8-77e6-8cb4-31b56184ad19" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-77e6-8cb4-31b56184ad19_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7262-90ef-06f2a5156fd9" 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_019fc884-1cc8-77e6-8cb4-31b56184ad19" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7262-90ef-06f2a5156fd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7e7d-a32d-5576d500bb42" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7262-90ef-06f2a5156fd9" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7e7d-a32d-5576d500bb42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727a-bede-d19ccbd473dd" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:to="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727a-bede-d19ccbd473dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727a-bede-d19ccbd473dd_default" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727a-bede-d19ccbd473dd" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-727a-bede-d19ccbd473dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-7c25-8824-93ac34f288b3" xlink:href="ida-20260930.xsd#ida_RegulatoryJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RegulatoryJurisdictionAxis_019fc884-1cc8-727a-bede-d19ccbd473dd" xlink:to="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-7c25-8824-93ac34f288b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesMember_01a159e5-7a2b-78b3-94b5-f4b61a4f943a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RegulatoryJurisdictionDomain_019fc884-1cc8-7c25-8824-93ac34f288b3" xlink:to="loc_us-gaap_PublicUtilitiesMember_01a159e5-7a2b-78b3-94b5-f4b61a4f943a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fc884-1cc8-786d-b39f-8b64bb5f9a97" 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_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fc884-1cc8-786d-b39f-8b64bb5f9a97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-786d-b39f-8b64bb5f9a97_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_019fc884-1cc8-786d-b39f-8b64bb5f9a97" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-786d-b39f-8b64bb5f9a97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-7947-bdc8-cb2b37de47c4" 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_019fc884-1cc8-786d-b39f-8b64bb5f9a97" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-7947-bdc8-cb2b37de47c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PrincipalamountofdebtsecuritiesinSellingAgreementMember_019fc884-1cc8-784b-ad32-0fbe96ff041c" xlink:href="ida-20260930.xsd#ida_PrincipalamountofdebtsecuritiesinSellingAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-7947-bdc8-cb2b37de47c4" xlink:to="loc_ida_PrincipalamountofdebtsecuritiesinSellingAgreementMember_019fc884-1cc8-784b-ad32-0fbe96ff041c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_FirstMortgageBonds4.85SeriesODue2036Domain_019fc884-1cc8-7d87-b0fb-396317b2e842" xlink:href="ida-20260930.xsd#ida_FirstMortgageBonds4.85SeriesODue2036Domain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-7947-bdc8-cb2b37de47c4" xlink:to="loc_ida_FirstMortgageBonds4.85SeriesODue2036Domain_019fc884-1cc8-7d87-b0fb-396317b2e842" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PollutionControlBond1.70Due2026Member_019fc884-1cc8-72fe-a77d-ec25c59c0cfd" xlink:href="ida-20260930.xsd#ida_PollutionControlBond1.70Due2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-7947-bdc8-cb2b37de47c4" xlink:to="loc_ida_PollutionControlBond1.70Due2026Member_019fc884-1cc8-72fe-a77d-ec25c59c0cfd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_FirstMortgageBonds5.70SeriesODue2055Domain_01a15f98-9661-7499-af79-5b865aeced55" xlink:href="ida-20260930.xsd#ida_FirstMortgageBonds5.70SeriesODue2055Domain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fc884-1cc8-7947-bdc8-cb2b37de47c4" xlink:to="loc_ida_FirstMortgageBonds5.70SeriesODue2055Domain_01a15f98-9661-7499-af79-5b865aeced55" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-7da4-8bbc-bbb0f44dc608" 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_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-7da4-8bbc-bbb0f44dc608" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7da4-8bbc-bbb0f44dc608_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_019fc884-1cc8-7da4-8bbc-bbb0f44dc608" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7da4-8bbc-bbb0f44dc608_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7c73-a1f0-6750057a186a" 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_019fc884-1cc8-7da4-8bbc-bbb0f44dc608" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7c73-a1f0-6750057a186a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7a85-853d-bca50f1af6dc" 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_019fc884-1cc8-7c73-a1f0-6750057a186a" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7a85-853d-bca50f1af6dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_01a15fac-6073-7d96-b1cd-c16101494f28" 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_DebtInstrumentTable_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_01a15fac-6073-7d96-b1cd-c16101494f28" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_01a15fac-6073-7d96-b1cd-c16101494f28_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_01a15fac-6073-7d96-b1cd-c16101494f28" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_01a15fac-6073-7d96-b1cd-c16101494f28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_01a15fac-6073-7402-be6d-8b0e564ec438" 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_01a15fac-6073-7d96-b1cd-c16101494f28" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_01a15fac-6073-7402-be6d-8b0e564ec438" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_01a15fac-6073-74a1-9f0f-1e840b2c072a" 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_01a15fac-6073-7402-be6d-8b0e564ec438" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_01a15fac-6073-74a1-9f0f-1e840b2c072a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_BondsIssuedAtReofferDebtAxis_01a17904-466d-703c-bc11-f3babf03aa57" xlink:href="ida-20260930.xsd#ida_BondsIssuedAtReofferDebtAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fc884-1cc8-7223-b1eb-63f80b3b313c" xlink:to="loc_ida_BondsIssuedAtReofferDebtAxis_01a17904-466d-703c-bc11-f3babf03aa57" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_BondsIssuedAtReofferDebtDomain_01a17904-466d-703c-bc11-f3babf03aa57_default" xlink:href="ida-20260930.xsd#ida_BondsIssuedAtReofferDebtDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_BondsIssuedAtReofferDebtAxis_01a17904-466d-703c-bc11-f3babf03aa57" xlink:to="loc_ida_BondsIssuedAtReofferDebtDomain_01a17904-466d-703c-bc11-f3babf03aa57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_BondsIssuedAtReofferDebtDomain_01a17904-466d-7070-85cd-e32e74c0cad1" xlink:href="ida-20260930.xsd#ida_BondsIssuedAtReofferDebtDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_BondsIssuedAtReofferDebtAxis_01a17904-466d-703c-bc11-f3babf03aa57" xlink:to="loc_ida_BondsIssuedAtReofferDebtDomain_01a17904-466d-7070-85cd-e32e74c0cad1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_MediumTermNotesSeriesOMember_01a17905-7692-787c-9043-ee12ab398a5b" xlink:href="ida-20260930.xsd#ida_MediumTermNotesSeriesOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_BondsIssuedAtReofferDebtDomain_01a17904-466d-7070-85cd-e32e74c0cad1" xlink:to="loc_ida_MediumTermNotesSeriesOMember_01a17905-7692-787c-9043-ee12ab398a5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019fc884-1cc8-7979-82b8-9c166203f17b" 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_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019fc884-1cc8-7979-82b8-9c166203f17b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_019fc884-1cc8-71ef-9c40-ca22facb88e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_019fc884-1cc8-71ef-9c40-ca22facb88e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fc884-1cc8-721c-aebd-fb6fd40e7a30" 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_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fc884-1cc8-721c-aebd-fb6fd40e7a30" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DebtInstrumentNetProceedsPlusAccruedInterest_01a17919-3e5e-743d-82cd-38e396165320" xlink:href="ida-20260930.xsd#ida_DebtInstrumentNetProceedsPlusAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_ida_DebtInstrumentNetProceedsPlusAccruedInterest_01a17919-3e5e-743d-82cd-38e396165320" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Debtinstrumentinterestratelimit_019fc884-1cc8-79e9-a210-e97b036cf938" xlink:href="ida-20260930.xsd#ida_Debtinstrumentinterestratelimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_ida_Debtinstrumentinterestratelimit_019fc884-1cc8-79e9-a210-e97b036cf938" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IndentureUnusedBorrowingCapacityAmount_019fc884-1cc8-76ce-819e-0030eb904f32" xlink:href="ida-20260930.xsd#ida_IndentureUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_ida_IndentureUnusedBorrowingCapacityAmount_019fc884-1cc8-76ce-819e-0030eb904f32" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IndentureLimitOfFirstMortgateBondsAtAnyOneTimeOutstanding_019fc884-1cc8-7ee6-8a29-e126a03724d1" xlink:href="ida-20260930.xsd#ida_IndentureLimitOfFirstMortgateBondsAtAnyOneTimeOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_ida_IndentureLimitOfFirstMortgateBondsAtAnyOneTimeOutstanding_019fc884-1cc8-7ee6-8a29-e126a03724d1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019fc884-1cc8-740d-93ec-053660352b29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019fc884-1cc8-740d-93ec-053660352b29" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PrincipalAmountOfDebtSecuritiesAndFirstMortgageBondsAuthorizedByTheIPUCOPUCAndWPSC._019fc884-1cc8-7fe0-b142-d82be77b0343" xlink:href="ida-20260930.xsd#ida_PrincipalAmountOfDebtSecuritiesAndFirstMortgageBondsAuthorizedByTheIPUCOPUCAndWPSC."/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fc884-1cc8-7bc6-8476-4ec974d9309b" xlink:to="loc_ida_PrincipalAmountOfDebtSecuritiesAndFirstMortgageBondsAuthorizedByTheIPUCOPUCAndWPSC._019fc884-1cc8-7fe0-b142-d82be77b0343" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/COMMONSTOCKLevel4Details" xlink:type="simple" xlink:href="ida-20260930.xsd#COMMONSTOCKLevel4Details"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/COMMONSTOCKLevel4Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:href="ida-20260930.xsd#ida_ShareholdersEquityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:href="ida-20260930.xsd#ida_ScheduleOfCommonStockIssuedDuringPeriodTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019fc884-1cc8-76c0-aa31-965be237991a" 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_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019fc884-1cc8-76c0-aa31-965be237991a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019fc884-1cc8-76c0-aa31-965be237991a_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_019fc884-1cc8-76c0-aa31-965be237991a" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019fc884-1cc8-76c0-aa31-965be237991a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019fc884-1cc8-7baf-84cc-28509eaeb9ab" 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_019fc884-1cc8-76c0-aa31-965be237991a" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019fc884-1cc8-7baf-84cc-28509eaeb9ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_019fc884-1cc8-7e24-a67e-20f6ee049390" 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_019fc884-1cc8-7baf-84cc-28509eaeb9ab" xlink:to="loc_srt_ParentCompanyMember_019fc884-1cc8-7e24-a67e-20f6ee049390" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ShareRecipientAxis_019fc884-1cc8-78f6-94a6-88079f4e7750" xlink:href="ida-20260930.xsd#ida_ShareRecipientAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:to="loc_ida_ShareRecipientAxis_019fc884-1cc8-78f6-94a6-88079f4e7750" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ShareRecipientDomain_019fc884-1cc8-78f6-94a6-88079f4e7750_default" xlink:href="ida-20260930.xsd#ida_ShareRecipientDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_ShareRecipientAxis_019fc884-1cc8-78f6-94a6-88079f4e7750" xlink:to="loc_ida_ShareRecipientDomain_019fc884-1cc8-78f6-94a6-88079f4e7750_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ShareRecipientDomain_019fc884-1cc8-7486-a8d8-ae13cee10e59" xlink:href="ida-20260930.xsd#ida_ShareRecipientDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_ShareRecipientAxis_019fc884-1cc8-78f6-94a6-88079f4e7750" xlink:to="loc_ida_ShareRecipientDomain_019fc884-1cc8-7486-a8d8-ae13cee10e59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-7eed-93a0-2e1b3d9bf80e" 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_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-7eed-93a0-2e1b3d9bf80e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7eed-93a0-2e1b3d9bf80e_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_019fc884-1cc8-7eed-93a0-2e1b3d9bf80e" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7eed-93a0-2e1b3d9bf80e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7950-a041-d6f7c3f5400f" 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_019fc884-1cc8-7eed-93a0-2e1b3d9bf80e" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7950-a041-d6f7c3f5400f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7e70-a486-30ce4b91502d" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7950-a041-d6f7c3f5400f" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7e70-a486-30ce4b91502d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019fc884-1cc8-75f7-8b1a-428daf424bce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019fc884-1cc8-75f7-8b1a-428daf424bce" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-75f7-8b1a-428daf424bce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019fc884-1cc8-75f7-8b1a-428daf424bce" xlink:to="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-75f7-8b1a-428daf424bce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019fc884-1cc8-75f7-8b1a-428daf424bce" xlink:to="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019fc884-1cc8-7571-af22-4fe3e144e888" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_us-gaap_PerformanceSharesMember_019fc884-1cc8-7571-af22-4fe3e144e888" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DirectorsMember_019fc884-1cc8-740e-9dc1-77c4d949b52c" xlink:href="ida-20260930.xsd#ida_DirectorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_DirectorsMember_019fc884-1cc8-740e-9dc1-77c4d949b52c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DividendReinvestmentAndStockPurchasePlanMember_019fc884-1cc8-7452-8216-9516266f450d" xlink:href="ida-20260930.xsd#ida_DividendReinvestmentAndStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_DividendReinvestmentAndStockPurchasePlanMember_019fc884-1cc8-7452-8216-9516266f450d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_EmployeeSavingsPlanMember_01a17a10-088c-7353-8803-7ffc0745f043" xlink:href="ida-20260930.xsd#ida_EmployeeSavingsPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_EmployeeSavingsPlanMember_01a17a10-088c-7353-8803-7ffc0745f043" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgram2024SeriesMember_019fc884-1cc8-7340-a459-0987a297a507" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgram2024SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_AtTheMarketOfferingProgram2024SeriesMember_019fc884-1cc8-7340-a459-0987a297a507" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgram2026SeriesMember_019fc884-1cc8-779c-bd45-7dae206c8a40" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgram2026SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_AtTheMarketOfferingProgram2026SeriesMember_019fc884-1cc8-779c-bd45-7dae206c8a40" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingPrograms20242026SeriesMember_019fc884-1cc8-7edb-bb60-5568e715c681" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingPrograms20242026SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_AtTheMarketOfferingPrograms20242026SeriesMember_019fc884-1cc8-7edb-bb60-5568e715c681" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity33127Member_019fc884-1cc8-790d-a187-d7821870572f" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity33127Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity33127Member_019fc884-1cc8-790d-a187-d7821870572f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity331271Member_019fc884-1cc8-7661-b0f7-616bb54752f6" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity331271Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity331271Member_019fc884-1cc8-7661-b0f7-616bb54752f6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity331272Member_019fc884-1cc8-7257-a1e6-47ddd35b4723" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity331272Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity331272Member_019fc884-1cc8-7257-a1e6-47ddd35b4723" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity52827Member_019fc884-1cc8-7dc1-9ba6-f189c803fb54" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity52827Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity52827Member_019fc884-1cc8-7dc1-9ba6-f189c803fb54" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity528271Member_019fc884-1cc8-78e5-9816-df87e79e6dcc" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity528271Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity528271Member_019fc884-1cc8-78e5-9816-df87e79e6dcc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity12327Member_019fc884-1cc8-7a4e-90a2-cdfc1d21735a" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity12327Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity12327Member_019fc884-1cc8-7a4e-90a2-cdfc1d21735a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity2292028Member_01a179d7-07db-7d09-a68a-157c4693b7b0" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity2292028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity2292028Member_01a179d7-07db-7d09-a68a-157c4693b7b0" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity22920281Member_01a179d7-70ca-7c72-9fa4-b72d5d65a37c" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity22920281Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity22920281Member_01a179d7-70ca-7c72-9fa4-b72d5d65a37c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsMaturity22920282Member_01a179d7-a0da-77aa-9680-9a81f2b11b9c" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsMaturity22920282Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsMaturity22920282Member_01a179d7-a0da-77aa-9680-9a81f2b11b9c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsSettlementDate33126Member_019fc884-1cc8-7644-959f-d33da867f846" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsSettlementDate33126Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsSettlementDate33126Member_019fc884-1cc8-7644-959f-d33da867f846" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ATMForwardSaleAgreementsSettlementDate331261Member_019fc884-1cc8-747d-82ef-2f794105cb76" xlink:href="ida-20260930.xsd#ida_ATMForwardSaleAgreementsSettlementDate331261Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ATMForwardSaleAgreementsSettlementDate331261Member_019fc884-1cc8-747d-82ef-2f794105cb76" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ForwardSaleAgreements2025SeriesMember_019fc884-1cc8-7f6d-a84e-3deb0f3f9332" xlink:href="ida-20260930.xsd#ida_ForwardSaleAgreements2025SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ForwardSaleAgreements2025SeriesMember_019fc884-1cc8-7f6d-a84e-3deb0f3f9332" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ForwardSaleAgreementsSettlementDate528262025SeriesMember_019fc884-1cc8-757f-a13c-5e2bad7e80b6" xlink:href="ida-20260930.xsd#ida_ForwardSaleAgreementsSettlementDate528262025SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ForwardSaleAgreementsSettlementDate528262025SeriesMember_019fc884-1cc8-757f-a13c-5e2bad7e80b6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ForwardSaleAgreementsSettlementDate713262025SeriesMember_019fc884-1cc8-7763-98b7-0230e282f036" xlink:href="ida-20260930.xsd#ida_ForwardSaleAgreementsSettlementDate713262025SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ForwardSaleAgreementsSettlementDate713262025SeriesMember_019fc884-1cc8-7763-98b7-0230e282f036" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ForwardSaleAgreementsSettlementDate101520262025SeriesMember_01a179d8-d5b7-76cf-8f55-d7dfb2c7f038" xlink:href="ida-20260930.xsd#ida_ForwardSaleAgreementsSettlementDate101520262025SeriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019fc884-1cc8-7498-bff2-87d9b8b030ea" xlink:to="loc_ida_ForwardSaleAgreementsSettlementDate101520262025SeriesMember_01a179d8-d5b7-76cf-8f55-d7dfb2c7f038" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-71dc-84b5-ad77ff6616ba" 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_ida_ScheduleOfCommonStockIssuedDuringPeriodTable_019fc884-1cc8-766d-889d-859818dca1bf" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-71dc-84b5-ad77ff6616ba" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-71dc-84b5-ad77ff6616ba_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_019fc884-1cc8-71dc-84b5-ad77ff6616ba" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-71dc-84b5-ad77ff6616ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7eec-9fb8-c8ccc9d71c8b" 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_019fc884-1cc8-71dc-84b5-ad77ff6616ba" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7eec-9fb8-c8ccc9d71c8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7dff-8fa7-a55eca3e4f3f" 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_019fc884-1cc8-7eec-9fb8-c8ccc9d71c8b" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7dff-8fa7-a55eca3e4f3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019fc884-1cc8-7a47-b578-4ca9dab498b6" 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_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019fc884-1cc8-7a47-b578-4ca9dab498b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019fc884-1cc8-722b-bbe9-1a0721e4c0dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019fc884-1cc8-722b-bbe9-1a0721e4c0dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgramMaximumValueOfSharesToBeIssuedGrossSalesPrice_019fc884-1cc8-7614-bfa8-19d1a85edf1e" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgramMaximumValueOfSharesToBeIssuedGrossSalesPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_AtTheMarketOfferingProgramMaximumValueOfSharesToBeIssuedGrossSalesPrice_019fc884-1cc8-7614-bfa8-19d1a85edf1e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgramInitialCommonSharesOffered_019fc884-1cc8-7afb-ac4d-4e5cddac1b63" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgramInitialCommonSharesOffered"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_AtTheMarketOfferingProgramInitialCommonSharesOffered_019fc884-1cc8-7afb-ac4d-4e5cddac1b63" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgramExecutedAmount_019fc884-1cc8-7593-8330-b988674e3292" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgramExecutedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_AtTheMarketOfferingProgramExecutedAmount_019fc884-1cc8-7593-8330-b988674e3292" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgramCommissionAndFeesAmount_019fc884-1cc8-79f1-8f31-3ee7420aa5cc" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgramCommissionAndFeesAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_AtTheMarketOfferingProgramCommissionAndFeesAmount_019fc884-1cc8-79f1-8f31-3ee7420aa5cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_AtTheMarketOfferingProgramRemainingValueOfSharesAvailableForIssuanceGrossSalesPrice_019fc884-1cc8-75cb-ae97-a6c60436ea93" xlink:href="ida-20260930.xsd#ida_AtTheMarketOfferingProgramRemainingValueOfSharesAvailableForIssuanceGrossSalesPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_AtTheMarketOfferingProgramRemainingValueOfSharesAvailableForIssuanceGrossSalesPrice_019fc884-1cc8-75cb-ae97-a6c60436ea93" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegisteredPublicOfferingInitialCommonSharesOffered_019fc884-1cc8-7284-bb7e-8e80fe58c14e" xlink:href="ida-20260930.xsd#ida_RegisteredPublicOfferingInitialCommonSharesOffered"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RegisteredPublicOfferingInitialCommonSharesOffered_019fc884-1cc8-7284-bb7e-8e80fe58c14e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegisteredPublicOfferingExecutedAmount_019fc884-1cc8-7698-a8e1-e44870907238" xlink:href="ida-20260930.xsd#ida_RegisteredPublicOfferingExecutedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RegisteredPublicOfferingExecutedAmount_019fc884-1cc8-7698-a8e1-e44870907238" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CashToBeReceivedOnSettlementOfForwardSaleAgreement_019fc884-1cc8-7043-b95e-1326474f8c24" xlink:href="ida-20260930.xsd#ida_CashToBeReceivedOnSettlementOfForwardSaleAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_CashToBeReceivedOnSettlementOfForwardSaleAgreement_019fc884-1cc8-7043-b95e-1326474f8c24" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ForwardSalePricePerShare_019fc884-1cc8-7a52-8925-8ec221eb8249" xlink:href="ida-20260930.xsd#ida_ForwardSalePricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_ForwardSalePricePerShare_019fc884-1cc8-7a52-8925-8ec221eb8249" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CashToDeliverToSettleForwardSalesAgreementNet_019fc884-1cc8-722a-944a-e8a8fa6d67af" xlink:href="ida-20260930.xsd#ida_CashToDeliverToSettleForwardSalesAgreementNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_CashToDeliverToSettleForwardSalesAgreementNet_019fc884-1cc8-722a-944a-e8a8fa6d67af" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CommonSharesToDeliverToSettleForwardSalesAgreementNet_019fc884-1cc8-7853-b341-2375c53d405a" xlink:href="ida-20260930.xsd#ida_CommonSharesToDeliverToSettleForwardSalesAgreementNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_CommonSharesToDeliverToSettleForwardSalesAgreementNet_019fc884-1cc8-7853-b341-2375c53d405a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CommonSharesDeliveredToSettleForwardSalesAgreementGross_019fc884-1cc8-759d-bb4c-de034ddba715" xlink:href="ida-20260930.xsd#ida_CommonSharesDeliveredToSettleForwardSalesAgreementGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_CommonSharesDeliveredToSettleForwardSalesAgreementGross_019fc884-1cc8-759d-bb4c-de034ddba715" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CashReceivedOnSettlementOfForwardSaleAgreement_019fc884-1cc8-7480-9d66-bdd5018333c4" xlink:href="ida-20260930.xsd#ida_CashReceivedOnSettlementOfForwardSaleAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_CashReceivedOnSettlementOfForwardSaleAgreement_019fc884-1cc8-7480-9d66-bdd5018333c4" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ForwardSalePricePerShareSettled_019fc884-1cc8-7d0c-8e7a-91b4cb824933" xlink:href="ida-20260930.xsd#ida_ForwardSalePricePerShareSettled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_ForwardSalePricePerShareSettled_019fc884-1cc8-7d0c-8e7a-91b4cb824933" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegisteredPublicOfferingPricePerShare_019fc884-1cc8-7827-ac81-e39340a2bab1" xlink:href="ida-20260930.xsd#ida_RegisteredPublicOfferingPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RegisteredPublicOfferingPricePerShare_019fc884-1cc8-7827-ac81-e39340a2bab1" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegisteredPublicOfferingInitialCommonSharesOfferedGreenshoe_019fc884-1cc8-7fe3-b7e6-13e29c162f30" xlink:href="ida-20260930.xsd#ida_RegisteredPublicOfferingInitialCommonSharesOfferedGreenshoe"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RegisteredPublicOfferingInitialCommonSharesOfferedGreenshoe_019fc884-1cc8-7fe3-b7e6-13e29c162f30" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegisteredPublicOfferingExecutedAmountGreenshoe_019fc884-1cc8-70e2-bc99-8155201b157d" xlink:href="ida-20260930.xsd#ida_RegisteredPublicOfferingExecutedAmountGreenshoe"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RegisteredPublicOfferingExecutedAmountGreenshoe_019fc884-1cc8-70e2-bc99-8155201b157d" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RegisteredPublicOfferingInitialCommonSharesOfferedTotal_019fc884-1cc8-7880-a3e9-66c6ba5eb2e9" xlink:href="ida-20260930.xsd#ida_RegisteredPublicOfferingInitialCommonSharesOfferedTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RegisteredPublicOfferingInitialCommonSharesOfferedTotal_019fc884-1cc8-7880-a3e9-66c6ba5eb2e9" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_InitialForwardSalePricePerShare_019fc884-1cc8-787d-b47a-9f296cb1b8bd" xlink:href="ida-20260930.xsd#ida_InitialForwardSalePricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_InitialForwardSalePricePerShare_019fc884-1cc8-787d-b47a-9f296cb1b8bd" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToEquityForwardAgreements_019fc884-1cc8-7c6e-9943-4798a17de7ec" 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_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToEquityForwardAgreements_019fc884-1cc8-7c6e-9943-4798a17de7ec" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromContributedCapital_019fc884-1cc8-7cb2-adc2-f616eeaf7f77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromContributedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_us-gaap_ProceedsFromContributedCapital_019fc884-1cc8-7cb2-adc2-f616eeaf7f77" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_MaximumLeverageRatioRequirement_019fc884-1cc8-71f1-a74a-b1e13930740f" xlink:href="ida-20260930.xsd#ida_MaximumLeverageRatioRequirement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_MaximumLeverageRatioRequirement_019fc884-1cc8-71f1-a74a-b1e13930740f" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RatioOfIndebtednessToNetCapital1_019fc884-1cc8-7c94-9999-eb0a4c8f927a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RatioOfIndebtednessToNetCapital1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_us-gaap_RatioOfIndebtednessToNetCapital1_019fc884-1cc8-7c94-9999-eb0a4c8f927a" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DividendDistributionRestrictionAmount_019fc884-1cc8-7899-a85d-3078262b6054" xlink:href="ida-20260930.xsd#ida_DividendDistributionRestrictionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_DividendDistributionRestrictionAmount_019fc884-1cc8-7899-a85d-3078262b6054" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DividendDistributionRestrictionThreshold_019fc884-1cc8-7fb8-b42a-c513e066ccfe" xlink:href="ida-20260930.xsd#ida_DividendDistributionRestrictionThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_DividendDistributionRestrictionThreshold_019fc884-1cc8-7fb8-b42a-c513e066ccfe" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RatioOfTotalCapitalToTotalCapitalAndLongTermDebt_019fc884-1cc8-7e60-8073-440e3b7f0114" xlink:href="ida-20260930.xsd#ida_RatioOfTotalCapitalToTotalCapitalAndLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_RatioOfTotalCapitalToTotalCapitalAndLongTermDebt_019fc884-1cc8-7e60-8073-440e3b7f0114" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019fc884-1cc8-7402-8940-bf72aa0da352" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_019fc884-1cc8-7402-8940-bf72aa0da352" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CommonSharesToDeliverToSettleForwardSalesAgreementGross_019fc884-1cc8-7f1d-a26f-b8b2fd9d15a7" xlink:href="ida-20260930.xsd#ida_CommonSharesToDeliverToSettleForwardSalesAgreementGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ShareholdersEquityLineItems_019fc884-1cc8-743a-b7c9-245514735fbd" xlink:to="loc_ida_CommonSharesToDeliverToSettleForwardSalesAgreementGross_019fc884-1cc8-7f1d-a26f-b8b2fd9d15a7" xlink:type="arc" order="29"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/COMMITMENTSPurchaseObligationsDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#COMMITMENTSPurchaseObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/COMMITMENTSPurchaseObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentLineItems_019fc884-1cc8-7098-af06-281d0f0e56d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_019fc884-1cc8-7098-af06-281d0f0e56d2" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019fc884-1cc8-792b-9c36-eaf3eef0617c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019fc884-1cc8-792b-9c36-eaf3eef0617c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-792b-9c36-eaf3eef0617c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019fc884-1cc8-792b-9c36-eaf3eef0617c" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-792b-9c36-eaf3eef0617c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019fc884-1cc8-792b-9c36-eaf3eef0617c" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_LongTermContractForPurchaseOfGasTransportationCapacityMember_019fc884-1cc8-7630-9d5f-9cc832420bc6" xlink:href="ida-20260930.xsd#ida_LongTermContractForPurchaseOfGasTransportationCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:to="loc_ida_LongTermContractForPurchaseOfGasTransportationCapacityMember_019fc884-1cc8-7630-9d5f-9cc832420bc6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalAdditionsMember_019fc884-1cc8-7268-b59c-a11d61a7b99c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalAdditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:to="loc_us-gaap_CapitalAdditionsMember_019fc884-1cc8-7268-b59c-a11d61a7b99c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_LongTermContractForPurchaseOfWindGenerationMember_01a17540-16ab-7635-a625-78e61b0b89a9" xlink:href="ida-20260930.xsd#ida_LongTermContractForPurchaseOfWindGenerationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:to="loc_ida_LongTermContractForPurchaseOfWindGenerationMember_01a17540-16ab-7635-a625-78e61b0b89a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_LongTermPowerForPurchaseOfSolarPowerAndBatteryStorageCapacityMember_01a17ede-eb56-768c-9c8a-13b298a6c35f" xlink:href="ida-20260930.xsd#ida_LongTermPowerForPurchaseOfSolarPowerAndBatteryStorageCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:to="loc_ida_LongTermPowerForPurchaseOfSolarPowerAndBatteryStorageCapacityMember_01a17ede-eb56-768c-9c8a-13b298a6c35f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_LongTermContractForPurchaseOfHydroPowerMember_01a17ee7-074e-76c1-a78b-712b339f957f" xlink:href="ida-20260930.xsd#ida_LongTermContractForPurchaseOfHydroPowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019fc884-1cc8-7a62-95fc-d4b4465a41b8" xlink:to="loc_ida_LongTermContractForPurchaseOfHydroPowerMember_01a17ee7-074e-76c1-a78b-712b339f957f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-758e-987f-d9770d0d339b" 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_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-758e-987f-d9770d0d339b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-758e-987f-d9770d0d339b_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_019fc884-1cc8-758e-987f-d9770d0d339b" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-758e-987f-d9770d0d339b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7d61-8f0a-09d153fbbfcc" 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_019fc884-1cc8-758e-987f-d9770d0d339b" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7d61-8f0a-09d153fbbfcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-76f7-84fb-8b20332e2291" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7d61-8f0a-09d153fbbfcc" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-76f7-84fb-8b20332e2291" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fc884-1cc8-73b2-9058-30745989b9a7" 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_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_srt_RangeAxis_019fc884-1cc8-73b2-9058-30745989b9a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fc884-1cc8-73b2-9058-30745989b9a7_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_019fc884-1cc8-73b2-9058-30745989b9a7" xlink:to="loc_srt_RangeMember_019fc884-1cc8-73b2-9058-30745989b9a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fc884-1cc8-7dd2-bedb-3815c633f63a" 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_019fc884-1cc8-73b2-9058-30745989b9a7" xlink:to="loc_srt_RangeMember_019fc884-1cc8-7dd2-bedb-3815c633f63a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_01a17e2b-a22a-7cc5-a65a-94c47e229b6d" 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_019fc884-1cc8-7dd2-bedb-3815c633f63a" xlink:to="loc_srt_MaximumMember_01a17e2b-a22a-7cc5-a65a-94c47e229b6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindPowerAxis_019fc884-1cc8-7f36-ba68-889747fbed2e" xlink:href="ida-20260930.xsd#ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindPowerAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindPowerAxis_019fc884-1cc8-7f36-ba68-889747fbed2e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindEnergyDomain_019fc884-1cc8-7f36-ba68-889747fbed2e_default" xlink:href="ida-20260930.xsd#ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindEnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindPowerAxis_019fc884-1cc8-7f36-ba68-889747fbed2e" xlink:to="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindEnergyDomain_019fc884-1cc8-7f36-ba68-889747fbed2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindEnergyDomain_019fc884-1cc8-764b-b719-be10bf5a636b" xlink:href="ida-20260930.xsd#ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindEnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindPowerAxis_019fc884-1cc8-7f36-ba68-889747fbed2e" xlink:to="loc_ida_TerminationOfContractsToAcquireAndOwnWindFacilityAndWindEnergyDomain_019fc884-1cc8-764b-b719-be10bf5a636b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-7ea1-9b17-175c03b5b119" 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_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-7ea1-9b17-175c03b5b119" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ea1-9b17-175c03b5b119_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_019fc884-1cc8-7ea1-9b17-175c03b5b119" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7ea1-9b17-175c03b5b119_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-78f8-b518-ee15f8db7736" 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_019fc884-1cc8-7ea1-9b17-175c03b5b119" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-78f8-b518-ee15f8db7736" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7e06-81be-054e3ae4b039" 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_019fc884-1cc8-78f8-b518-ee15f8db7736" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7e06-81be-054e3ae4b039" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019fc884-1cc8-734c-a091-6bcd03f774a5" 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_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_srt_StatementScenarioAxis_019fc884-1cc8-734c-a091-6bcd03f774a5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-734c-a091-6bcd03f774a5_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_019fc884-1cc8-734c-a091-6bcd03f774a5" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-734c-a091-6bcd03f774a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-74fe-8f37-18cd369b4b6a" 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_019fc884-1cc8-734c-a091-6bcd03f774a5" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc8-74fe-8f37-18cd369b4b6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019fc884-1cc8-704e-a5fd-6b72c1c55080" 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_019fc884-1cc8-74fe-8f37-18cd369b4b6a" xlink:to="loc_srt_ScenarioForecastMember_019fc884-1cc8-704e-a5fd-6b72c1c55080" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PURPAAndNonPURPAPowerProductionAxis_019fc884-1cc8-711c-baef-eef4e723e920" xlink:href="ida-20260930.xsd#ida_PURPAAndNonPURPAPowerProductionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_019fc884-1cc8-7231-8b47-a2e6135311ba" xlink:to="loc_ida_PURPAAndNonPURPAPowerProductionAxis_019fc884-1cc8-711c-baef-eef4e723e920" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PURPAAndNonPURPAPowerProductionDomain_019fc884-1cc8-711c-baef-eef4e723e920_default" xlink:href="ida-20260930.xsd#ida_PURPAAndNonPURPAPowerProductionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_PURPAAndNonPURPAPowerProductionAxis_019fc884-1cc8-711c-baef-eef4e723e920" xlink:to="loc_ida_PURPAAndNonPURPAPowerProductionDomain_019fc884-1cc8-711c-baef-eef4e723e920_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PURPAAndNonPURPAPowerProductionDomain_019fc884-1cc8-769e-93ed-991c0572a23c" xlink:href="ida-20260930.xsd#ida_PURPAAndNonPURPAPowerProductionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_PURPAAndNonPURPAPowerProductionAxis_019fc884-1cc8-711c-baef-eef4e723e920" xlink:to="loc_ida_PURPAAndNonPURPAPowerProductionDomain_019fc884-1cc8-769e-93ed-991c0572a23c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PURPAAndNonPURPAPowerProductionMember_019fc884-1cc8-7f2d-b6bd-e9493d65cbb4" xlink:href="ida-20260930.xsd#ida_PURPAAndNonPURPAPowerProductionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_PURPAAndNonPURPAPowerProductionDomain_019fc884-1cc8-769e-93ed-991c0572a23c" xlink:to="loc_ida_PURPAAndNonPURPAPowerProductionMember_019fc884-1cc8-7f2d-b6bd-e9493d65cbb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_PURPAAndNonPURPAPowerProductionEnergyStorageMember_019fc884-1cc8-7bb3-8544-a2a0d3231569" xlink:href="ida-20260930.xsd#ida_PURPAAndNonPURPAPowerProductionEnergyStorageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_PURPAAndNonPURPAPowerProductionDomain_019fc884-1cc8-769e-93ed-991c0572a23c" xlink:to="loc_ida_PURPAAndNonPURPAPowerProductionEnergyStorageMember_019fc884-1cc8-7bb3-8544-a2a0d3231569" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PurchaseObligation_019fc884-1cc8-7bc6-90f3-57d8aed7e16e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PurchaseObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_019fc884-1cc8-7098-af06-281d0f0e56d2" xlink:to="loc_us-gaap_PurchaseObligation_019fc884-1cc8-7bc6-90f3-57d8aed7e16e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_NameplateCapacity_019fc884-1cc8-7762-8a84-01d913f2211e" xlink:href="ida-20260930.xsd#ida_NameplateCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_019fc884-1cc8-7098-af06-281d0f0e56d2" xlink:to="loc_ida_NameplateCapacity_019fc884-1cc8-7762-8a84-01d913f2211e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermPurchaseCommitmentPeriod_019fc884-1cc8-719a-9148-ceee7ae0af72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermPurchaseCommitmentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_019fc884-1cc8-7098-af06-281d0f0e56d2" xlink:to="loc_us-gaap_LongtermPurchaseCommitmentPeriod_019fc884-1cc8-719a-9148-ceee7ae0af72" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/COMMITMENTSGuaranteesDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#COMMITMENTSGuaranteesDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/COMMITMENTSGuaranteesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsLineItems_019fc884-1cc8-7b62-8848-5f95f13ebcec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_019fc884-1cc8-7a26-8b54-be6c96ff3298" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfGuaranteeObligationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_019fc884-1cc8-7b62-8848-5f95f13ebcec" xlink:to="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_019fc884-1cc8-7a26-8b54-be6c96ff3298" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-7c68-8bb6-75c991c4c183" 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_ScheduleOfGuaranteeObligationsTable_019fc884-1cc8-7a26-8b54-be6c96ff3298" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-7c68-8bb6-75c991c4c183" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7c68-8bb6-75c991c4c183_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_019fc884-1cc8-7c68-8bb6-75c991c4c183" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7c68-8bb6-75c991c4c183_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7935-aa64-33846077c74b" 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_019fc884-1cc8-7c68-8bb6-75c991c4c183" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7935-aa64-33846077c74b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7d87-9465-1289ef72acd3" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7935-aa64-33846077c74b" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7d87-9465-1289ef72acd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_BridgerCoalCompanyMember_019fc884-1cc8-7656-99be-48e891d4e36a" xlink:href="ida-20260930.xsd#ida_BridgerCoalCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7935-aa64-33846077c74b" xlink:to="loc_ida_BridgerCoalCompanyMember_019fc884-1cc8-7656-99be-48e891d4e36a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsMaximumExposure_019fc884-1cc8-70e3-a57d-c3985168f84b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsMaximumExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_019fc884-1cc8-7b62-8848-5f95f13ebcec" xlink:to="loc_us-gaap_GuaranteeObligationsMaximumExposure_019fc884-1cc8-70e3-a57d-c3985168f84b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/BENEFITPLANSLevel4Details" xlink:type="simple" xlink:href="ida-20260930.xsd#BENEFITPLANSLevel4Details"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/BENEFITPLANSLevel4Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" 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_019fc884-1cc8-7b59-80a0-a5a2f4f1cf3d" 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_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019fc884-1cc8-7b59-80a0-a5a2f4f1cf3d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019fc884-1cc8-7e88-951d-c4ee8cc1dfd1" 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_019fc884-1cc8-7b59-80a0-a5a2f4f1cf3d" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019fc884-1cc8-7e88-951d-c4ee8cc1dfd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019fc884-1cc8-7e88-951d-c4ee8cc1dfd1_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_019fc884-1cc8-7e88-951d-c4ee8cc1dfd1" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019fc884-1cc8-7e88-951d-c4ee8cc1dfd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019fc884-1cc8-7e17-8efc-f361319a1f30" 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_019fc884-1cc8-7e88-951d-c4ee8cc1dfd1" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019fc884-1cc8-7e17-8efc-f361319a1f30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019fc884-1cc8-7404-8a31-5549a3c610d5" 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_019fc884-1cc8-7e17-8efc-f361319a1f30" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019fc884-1cc8-7404-8a31-5549a3c610d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_019fc884-1cc8-778a-9329-674af5b92bea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019fc884-1cc8-7e17-8efc-f361319a1f30" xlink:to="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_019fc884-1cc8-778a-9329-674af5b92bea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019fc884-1cc8-718a-9e48-3d81c9acf4d0" 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_019fc884-1cc8-7e17-8efc-f361319a1f30" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019fc884-1cc8-718a-9e48-3d81c9acf4d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-7cf5-9a77-bf00fa90ee4c" 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_ScheduleOfDefinedBenefitPlansDisclosuresTable_019fc884-1cc8-7b59-80a0-a5a2f4f1cf3d" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc8-7cf5-9a77-bf00fa90ee4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7cf5-9a77-bf00fa90ee4c_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_019fc884-1cc8-7cf5-9a77-bf00fa90ee4c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7cf5-9a77-bf00fa90ee4c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7429-8b02-cebb5a878800" 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_019fc884-1cc8-7cf5-9a77-bf00fa90ee4c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc8-7429-8b02-cebb5a878800" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7f8c-b584-51716093e39d" 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_019fc884-1cc8-7429-8b02-cebb5a878800" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc8-7f8c-b584-51716093e39d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc8-7769-a681-b7c6ad71af5c" 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_ScheduleOfDefinedBenefitPlansDisclosuresTable_019fc884-1cc8-7b59-80a0-a5a2f4f1cf3d" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc8-7769-a681-b7c6ad71af5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7769-a681-b7c6ad71af5c_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_019fc884-1cc8-7769-a681-b7c6ad71af5c" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7769-a681-b7c6ad71af5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc8-7a1d-b020-9beccec19ffc" 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_019fc884-1cc8-7769-a681-b7c6ad71af5c" xlink:to="loc_dei_EntityDomain_019fc884-1cc8-7a1d-b020-9beccec19ffc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7605-bf9f-668ff8e5487f" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc8-7a1d-b020-9beccec19ffc" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc8-7605-bf9f-668ff8e5487f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DefinedBenefitPlansNumberOfPlans_019fc884-1cc9-7f5c-8c2c-3384b27ed25e" xlink:href="ida-20260930.xsd#ida_DefinedBenefitPlansNumberOfPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_ida_DefinedBenefitPlansNumberOfPlans_019fc884-1cc9-7f5c-8c2c-3384b27ed25e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_019fc884-1cc9-7d4e-85b1-e2e4ca9e1227" 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_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_019fc884-1cc9-7d4e-85b1-e2e4ca9e1227" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_019fc884-1cc9-7ecb-8f91-174f6a6ffe8c" 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_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_019fc884-1cc9-7ecb-8f91-174f6a6ffe8c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019fc884-1cc9-7f82-906b-874586cb6f07" 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_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019fc884-1cc9-7f82-906b-874586cb6f07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019fc884-1cc9-72b7-aacf-554e57149606" 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_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019fc884-1cc9-72b7-aacf-554e57149606" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019fc884-1cc9-7d3a-8255-be8c50a1632a" 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_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019fc884-1cc9-7d3a-8255-be8c50a1632a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019fc884-1cc9-7608-9d5d-8d413d94716d" 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_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019fc884-1cc9-7608-9d5d-8d413d94716d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DefinedBenefitPlanRegulatoryAdjustmentsDeferred_019fc884-1cc9-7085-b14a-c014063ffe94" xlink:href="ida-20260930.xsd#ida_DefinedBenefitPlanRegulatoryAdjustmentsDeferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_ida_DefinedBenefitPlanRegulatoryAdjustmentsDeferred_019fc884-1cc9-7085-b14a-c014063ffe94" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DefinedBenefitPlanRegulatedIPUCAuthorizedrecoveredpensioncost_019fc884-1cc9-772b-95dd-0680ce18f784" xlink:href="ida-20260930.xsd#ida_DefinedBenefitPlanRegulatedIPUCAuthorizedrecoveredpensioncost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_ida_DefinedBenefitPlanRegulatedIPUCAuthorizedrecoveredpensioncost_019fc884-1cc9-772b-95dd-0680ce18f784" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DefinedBenefitPlanNetPeriodicBenefitCostAfterRegulatoryAdjustments_019fc884-1cc9-7bde-831e-fb9d59bafe3a" xlink:href="ida-20260930.xsd#ida_DefinedBenefitPlanNetPeriodicBenefitCostAfterRegulatoryAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_ida_DefinedBenefitPlanNetPeriodicBenefitCostAfterRegulatoryAdjustments_019fc884-1cc9-7bde-831e-fb9d59bafe3a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_NetServiceCostDefinedBenefitPlan_019fc884-1cc9-7587-b20e-5d6707b91f79" xlink:href="ida-20260930.xsd#ida_NetServiceCostDefinedBenefitPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_ida_NetServiceCostDefinedBenefitPlan_019fc884-1cc9-7587-b20e-5d6707b91f79" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_Otherexpensedefinedbenefitplanbenefitcost_019fc884-1cc9-7513-81c1-02cd9894fff0" xlink:href="ida-20260930.xsd#ida_Otherexpensedefinedbenefitplanbenefitcost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_ida_Otherexpensedefinedbenefitplanbenefitcost_019fc884-1cc9-7513-81c1-02cd9894fff0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_019fc884-1cc9-7963-afc2-eee29b3c94d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019fc884-1cc9-7306-8648-5bf05c052fbd" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_019fc884-1cc9-7963-afc2-eee29b3c94d7" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/DerivativeInstrumentsGainsLossonDerivativesRecognizedinIncomeDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#DerivativeInstrumentsGainsLossonDerivativesRecognizedinIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/DerivativeInstrumentsGainsLossonDerivativesRecognizedinIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019fc884-1cc9-7822-ab2a-a14c3a079946" 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_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" 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_019fc884-1cc9-7822-ab2a-a14c3a079946" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-7b98-9dce-4a913036c535" 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_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-7b98-9dce-4a913036c535" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7b98-9dce-4a913036c535_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_019fc884-1cc9-7b98-9dce-4a913036c535" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7b98-9dce-4a913036c535_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-77c1-a48f-f85271624d4a" 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_019fc884-1cc9-7b98-9dce-4a913036c535" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-77c1-a48f-f85271624d4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-7e87-8202-bf395421f853" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnergyRelatedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-77c1-a48f-f85271624d4a" xlink:to="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-7e87-8202-bf395421f853" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019fc884-1cc9-73e8-8c53-adafee1ffcd4" 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_019fc884-1cc9-77c1-a48f-f85271624d4a" xlink:to="loc_us-gaap_CommodityContractMember_019fc884-1cc9-73e8-8c53-adafee1ffcd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fc884-1cc9-7159-b56b-4458829f5908" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fc884-1cc9-7159-b56b-4458829f5908" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019fc884-1cc9-7394-bdf2-ab801f300bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019fc884-1cc9-7822-ab2a-a14c3a079946" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019fc884-1cc9-7394-bdf2-ab801f300bf7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/DerivativeInstrumentsGainsLossonDerivativesRecognizedinIncomeDetails_1" xlink:type="simple" xlink:href="ida-20260930.xsd#DerivativeInstrumentsGainsLossonDerivativesRecognizedinIncomeDetails_1"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/DerivativeInstrumentsGainsLossonDerivativesRecognizedinIncomeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019fc884-1cc9-7822-ab2a-a14c3a079946" 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_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" 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_019fc884-1cc9-7822-ab2a-a14c3a079946" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-7b98-9dce-4a913036c535" 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_019fc884-1cc9-7a4f-9a64-87d718e9d6d2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-7b98-9dce-4a913036c535" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7b98-9dce-4a913036c535_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_019fc884-1cc9-7b98-9dce-4a913036c535" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7b98-9dce-4a913036c535_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-77c1-a48f-f85271624d4a" 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_019fc884-1cc9-7b98-9dce-4a913036c535" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-77c1-a48f-f85271624d4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-7e87-8202-bf395421f853" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnergyRelatedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-77c1-a48f-f85271624d4a" xlink:to="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-7e87-8202-bf395421f853" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019fc884-1cc9-73e8-8c53-adafee1ffcd4" 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_019fc884-1cc9-77c1-a48f-f85271624d4a" xlink:to="loc_us-gaap_CommodityContractMember_019fc884-1cc9-73e8-8c53-adafee1ffcd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019fc884-1cc9-7394-bdf2-ab801f300bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019fc884-1cc9-7822-ab2a-a14c3a079946" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019fc884-1cc9-7394-bdf2-ab801f300bf7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/DerivativeInstrumentsFairValueandOffsetsTableDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#DerivativeInstrumentsFairValueandOffsetsTableDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/DerivativeInstrumentsFairValueandOffsetsTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" 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_019fc884-1cc9-7efa-9b29-d598c7d3d409" 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_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fc884-1cc9-7efa-9b29-d598c7d3d409" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-75c0-bf80-446b6ffd8956" 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_019fc884-1cc9-7efa-9b29-d598c7d3d409" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-75c0-bf80-446b6ffd8956" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-75c0-bf80-446b6ffd8956_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_019fc884-1cc9-75c0-bf80-446b6ffd8956" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-75c0-bf80-446b6ffd8956_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7f00-ba11-bc981d2cef70" 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_019fc884-1cc9-75c0-bf80-446b6ffd8956" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7f00-ba11-bc981d2cef70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-728f-8ef6-3356f4c41b85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnergyRelatedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7f00-ba11-bc981d2cef70" xlink:to="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-728f-8ef6-3356f4c41b85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019fc884-1cc9-759f-86c7-95f1454190f8" 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_019fc884-1cc9-7f00-ba11-bc981d2cef70" xlink:to="loc_us-gaap_CommodityContractMember_019fc884-1cc9-759f-86c7-95f1454190f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fc884-1cc9-745b-883d-d9fc7c0496f2" 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_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fc884-1cc9-7efa-9b29-d598c7d3d409" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fc884-1cc9-745b-883d-d9fc7c0496f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fc884-1cc9-78db-9c99-80df31e00cd0" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fc884-1cc9-78db-9c99-80df31e00cd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019fc884-1cc9-7dc0-aed1-4960a737da35" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019fc884-1cc9-7dc0-aed1-4960a737da35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019fc884-1cc9-7008-92a9-d889effa209d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019fc884-1cc9-7008-92a9-d889effa209d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fc884-1cc9-7342-89a8-7d719defa965" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fc884-1cc9-7342-89a8-7d719defa965" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019fc884-1cc9-76fd-93be-07d276030544" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019fc884-1cc9-76fd-93be-07d276030544" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019fc884-1cc9-7c3c-8c28-51e2f11df4f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019fc884-1cc9-7c3c-8c28-51e2f11df4f2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_019fc884-1cc9-7055-b715-6dfb86f3fdfc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_019fc884-1cc9-7055-b715-6dfb86f3fdfc" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/DerivativeInstrumentsFairValueandOffsetsTableDetails_1" xlink:type="simple" xlink:href="ida-20260930.xsd#DerivativeInstrumentsFairValueandOffsetsTableDetails_1"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/DerivativeInstrumentsFairValueandOffsetsTableDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" 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_019fc884-1cc9-7efa-9b29-d598c7d3d409" 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_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fc884-1cc9-7efa-9b29-d598c7d3d409" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-75c0-bf80-446b6ffd8956" 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_019fc884-1cc9-7efa-9b29-d598c7d3d409" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fc884-1cc9-75c0-bf80-446b6ffd8956" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-75c0-bf80-446b6ffd8956_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_019fc884-1cc9-75c0-bf80-446b6ffd8956" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-75c0-bf80-446b6ffd8956_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7f00-ba11-bc981d2cef70" 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_019fc884-1cc9-75c0-bf80-446b6ffd8956" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7f00-ba11-bc981d2cef70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-728f-8ef6-3356f4c41b85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnergyRelatedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fc884-1cc9-7f00-ba11-bc981d2cef70" xlink:to="loc_us-gaap_EnergyRelatedDerivativeMember_019fc884-1cc9-728f-8ef6-3356f4c41b85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019fc884-1cc9-759f-86c7-95f1454190f8" 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_019fc884-1cc9-7f00-ba11-bc981d2cef70" xlink:to="loc_us-gaap_CommodityContractMember_019fc884-1cc9-759f-86c7-95f1454190f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fc884-1cc9-78db-9c99-80df31e00cd0" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fc884-1cc9-78db-9c99-80df31e00cd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019fc884-1cc9-7dc0-aed1-4960a737da35" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019fc884-1cc9-7dc0-aed1-4960a737da35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019fc884-1cc9-7008-92a9-d889effa209d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019fc884-1cc9-7008-92a9-d889effa209d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fc884-1cc9-7342-89a8-7d719defa965" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fc884-1cc9-7342-89a8-7d719defa965" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019fc884-1cc9-76fd-93be-07d276030544" 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_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019fc884-1cc9-76fd-93be-07d276030544" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019fc884-1cc9-7c3c-8c28-51e2f11df4f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019fc884-1cc9-7c3c-8c28-51e2f11df4f2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_019fc884-1cc9-7055-b715-6dfb86f3fdfc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fc884-1cc9-7c0f-bc64-b9f44d896dfd" xlink:to="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_019fc884-1cc9-7055-b715-6dfb86f3fdfc" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/DerivativeCommoditiesandDisclosuresDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#DerivativeCommoditiesandDisclosuresDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/DerivativeCommoditiesandDisclosuresDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019fc884-1cc9-7df2-8052-ed24ac41096e" 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_019fc884-1cc9-70dc-8e39-ea14f47bf869" 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_019fc884-1cc9-7df2-8052-ed24ac41096e" xlink:to="loc_us-gaap_DerivativeTable_019fc884-1cc9-70dc-8e39-ea14f47bf869" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_019fc884-1cc9-7f27-aa96-8407087f1840" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019fc884-1cc9-70dc-8e39-ea14f47bf869" xlink:to="loc_srt_EnergyAxis_019fc884-1cc9-7f27-aa96-8407087f1840" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019fc884-1cc9-7f27-aa96-8407087f1840_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_019fc884-1cc9-7f27-aa96-8407087f1840" xlink:to="loc_srt_EnergyDomain_019fc884-1cc9-7f27-aa96-8407087f1840_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019fc884-1cc9-7bb3-8613-ba053e6137da" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_019fc884-1cc9-7f27-aa96-8407087f1840" xlink:to="loc_srt_EnergyDomain_019fc884-1cc9-7bb3-8613-ba053e6137da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ElectricityMember_019fc884-1cc9-718f-994b-6aa11c05cb7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ElectricityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019fc884-1cc9-7bb3-8613-ba053e6137da" xlink:to="loc_us-gaap_ElectricityMember_019fc884-1cc9-718f-994b-6aa11c05cb7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_FuelMember_019fc884-1cc9-77b7-9cc6-457910d4be89" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_FuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019fc884-1cc9-7bb3-8613-ba053e6137da" xlink:to="loc_srt_FuelMember_019fc884-1cc9-77b7-9cc6-457910d4be89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_019fc884-1cc9-775e-8dfd-dde51a0a9820" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019fc884-1cc9-70dc-8e39-ea14f47bf869" xlink:to="loc_us-gaap_PositionAxis_019fc884-1cc9-775e-8dfd-dde51a0a9820" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_019fc884-1cc9-775e-8dfd-dde51a0a9820_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_019fc884-1cc9-775e-8dfd-dde51a0a9820" xlink:to="loc_us-gaap_PositionDomain_019fc884-1cc9-775e-8dfd-dde51a0a9820_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_019fc884-1cc9-75cb-9261-2636426bc977" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_019fc884-1cc9-775e-8dfd-dde51a0a9820" xlink:to="loc_us-gaap_PositionDomain_019fc884-1cc9-75cb-9261-2636426bc977" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_019fc884-1cc9-7af0-81b8-f17f1fe849a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_019fc884-1cc9-75cb-9261-2636426bc977" xlink:to="loc_us-gaap_LongMember_019fc884-1cc9-7af0-81b8-f17f1fe849a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_019fc884-1cc9-7f14-bd0b-53228b8e2414" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_019fc884-1cc9-75cb-9261-2636426bc977" xlink:to="loc_us-gaap_ShortMember_019fc884-1cc9-7f14-bd0b-53228b8e2414" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019fc884-1cc9-78aa-a507-d6c7509f7a3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019fc884-1cc9-7df2-8052-ed24ac41096e" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019fc884-1cc9-78aa-a507-d6c7509f7a3b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/FAIRVALUEMEASUREMENTSLevel4Details" xlink:type="simple" xlink:href="ida-20260930.xsd#FAIRVALUEMEASUREMENTSLevel4Details"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/FAIRVALUEMEASUREMENTSLevel4Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fc884-1cc9-77cc-91ad-63c447019f79" 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_019fc884-1cc9-7be7-835c-e62e3e52feb0" 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_019fc884-1cc9-77cc-91ad-63c447019f79" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fc884-1cc9-7be7-835c-e62e3e52feb0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fc884-1cc9-74d2-8209-41bc526e8336" 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_019fc884-1cc9-7be7-835c-e62e3e52feb0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fc884-1cc9-74d2-8209-41bc526e8336" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fc884-1cc9-74d2-8209-41bc526e8336_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_019fc884-1cc9-74d2-8209-41bc526e8336" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fc884-1cc9-74d2-8209-41bc526e8336_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fc884-1cc9-76a1-ae57-6c62415b349f" 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_019fc884-1cc9-74d2-8209-41bc526e8336" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fc884-1cc9-76a1-ae57-6c62415b349f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019fc884-1cc9-7213-b18e-d0c6f8e02491" 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_019fc884-1cc9-76a1-ae57-6c62415b349f" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019fc884-1cc9-7213-b18e-d0c6f8e02491" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019fc884-1cc9-76b4-bcb2-1e2efaa64487" 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_019fc884-1cc9-76a1-ae57-6c62415b349f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019fc884-1cc9-76b4-bcb2-1e2efaa64487" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019fc884-1cc9-7aee-9d71-dfb6169b10c3" 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_019fc884-1cc9-76a1-ae57-6c62415b349f" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019fc884-1cc9-7aee-9d71-dfb6169b10c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019fc884-1cc9-75c2-98ed-8ca28976f4d5" 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_019fc884-1cc9-76a1-ae57-6c62415b349f" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019fc884-1cc9-75c2-98ed-8ca28976f4d5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc9-7a63-9f2b-c6465ad8a68c" 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_019fc884-1cc9-7be7-835c-e62e3e52feb0" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc9-7a63-9f2b-c6465ad8a68c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-7a63-9f2b-c6465ad8a68c_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_019fc884-1cc9-7a63-9f2b-c6465ad8a68c" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-7a63-9f2b-c6465ad8a68c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-7dbe-9c3b-4c2592589338" 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_019fc884-1cc9-7a63-9f2b-c6465ad8a68c" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-7dbe-9c3b-4c2592589338" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-75ea-9308-58e666315ece" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc9-7dbe-9c3b-4c2592589338" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-75ea-9308-58e666315ece" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019fc884-1cc9-7238-b30d-de75b1a87c66" 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fc884-1cc9-77cc-91ad-63c447019f79" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019fc884-1cc9-7238-b30d-de75b1a87c66" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019fc884-1cc9-7599-961e-90a1099e5077" 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fc884-1cc9-77cc-91ad-63c447019f79" xlink:to="loc_us-gaap_DerivativeAssets_019fc884-1cc9-7599-961e-90a1099e5077" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNi_019fc884-1cc9-7171-8607-f6d8783550ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNi"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fc884-1cc9-77cc-91ad-63c447019f79" xlink:to="loc_us-gaap_EquitySecuritiesFvNi_019fc884-1cc9-7171-8607-f6d8783550ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019fc884-1cc9-7eba-9a06-acdebfbb5c41" 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fc884-1cc9-77cc-91ad-63c447019f79" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019fc884-1cc9-7eba-9a06-acdebfbb5c41" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019fc884-1cc9-768c-90a4-a1ffb2c5885c" 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fc884-1cc9-77cc-91ad-63c447019f79" xlink:to="loc_us-gaap_DerivativeLiabilities_019fc884-1cc9-768c-90a4-a1ffb2c5885c" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/FAIRVALUEMEASUREMENTSFairValuebyBalanceSheetGroupingDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#FAIRVALUEMEASUREMENTSFairValuebyBalanceSheetGroupingDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/FAIRVALUEMEASUREMENTSFairValuebyBalanceSheetGroupingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fc884-1cc9-76d1-8e51-fd7dd5769a46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fc884-1cc9-7f50-81c5-50ed974d7fd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fc884-1cc9-76d1-8e51-fd7dd5769a46" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fc884-1cc9-7f50-81c5-50ed974d7fd5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019fc884-1cc9-7c75-bfee-7a954cc5362c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019fc884-1cc9-7f50-81c5-50ed974d7fd5" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019fc884-1cc9-7c75-bfee-7a954cc5362c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fc884-1cc9-7c75-bfee-7a954cc5362c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019fc884-1cc9-7c75-bfee-7a954cc5362c" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fc884-1cc9-7c75-bfee-7a954cc5362c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fc884-1cc9-7eeb-8b8c-5b2850ae52aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019fc884-1cc9-7c75-bfee-7a954cc5362c" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fc884-1cc9-7eeb-8b8c-5b2850ae52aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fc884-1cc9-7ffc-a1af-f404c3dc2345" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fc884-1cc9-7eeb-8b8c-5b2850ae52aa" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019fc884-1cc9-7ffc-a1af-f404c3dc2345" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019fc884-1cc9-74a4-a319-63a62c9587e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fc884-1cc9-7eeb-8b8c-5b2850ae52aa" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019fc884-1cc9-74a4-a319-63a62c9587e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019fc884-1cc9-735b-9b4b-c67161d57a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019fc884-1cc9-7eeb-8b8c-5b2850ae52aa" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019fc884-1cc9-735b-9b4b-c67161d57a5a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc9-79bd-bd32-2d609778f85b" 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_FairValueByBalanceSheetGroupingTable_019fc884-1cc9-7f50-81c5-50ed974d7fd5" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc9-79bd-bd32-2d609778f85b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-79bd-bd32-2d609778f85b_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_019fc884-1cc9-79bd-bd32-2d609778f85b" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-79bd-bd32-2d609778f85b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-77b6-9610-3acb66017bad" 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_019fc884-1cc9-79bd-bd32-2d609778f85b" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-77b6-9610-3acb66017bad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-75f3-be76-0c04888b9784" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc9-77b6-9610-3acb66017bad" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-75f3-be76-0c04888b9784" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fc884-1cc9-7b2e-bac0-2ac61fa8421f" 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_FairValueByBalanceSheetGroupingTable_019fc884-1cc9-7f50-81c5-50ed974d7fd5" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fc884-1cc9-7b2e-bac0-2ac61fa8421f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fc884-1cc9-7b2e-bac0-2ac61fa8421f_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_019fc884-1cc9-7b2e-bac0-2ac61fa8421f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fc884-1cc9-7b2e-bac0-2ac61fa8421f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fc884-1cc9-7c90-a847-54aa1d5cb259" 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_019fc884-1cc9-7b2e-bac0-2ac61fa8421f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fc884-1cc9-7c90-a847-54aa1d5cb259" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_CorporateFixedIncomeAndAssetBackedDebtSecuritiesMember_019fc884-1cc9-76eb-a54e-5e669a9e390a" xlink:href="ida-20260930.xsd#ida_CorporateFixedIncomeAndAssetBackedDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fc884-1cc9-7c90-a847-54aa1d5cb259" xlink:to="loc_ida_CorporateFixedIncomeAndAssetBackedDebtSecuritiesMember_019fc884-1cc9-76eb-a54e-5e669a9e390a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_019fc884-1cc9-71c5-9b0d-f6aba19f114d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fc884-1cc9-76d1-8e51-fd7dd5769a46" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_019fc884-1cc9-71c5-9b0d-f6aba19f114d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_019fc884-1cc9-7f5a-890f-fe080868b553" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fc884-1cc9-76d1-8e51-fd7dd5769a46" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_019fc884-1cc9-7f5a-890f-fe080868b553" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019fc884-1cc9-7cb7-9ee9-f7c4b451ec32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fc884-1cc9-76d1-8e51-fd7dd5769a46" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019fc884-1cc9-7cb7-9ee9-f7c4b451ec32" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue_019fc884-1cc9-75fc-a179-e07b2f683b6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019fc884-1cc9-76d1-8e51-fd7dd5769a46" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue_019fc884-1cc9-75fc-a179-e07b2f683b6e" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/SEGMENTINFORMATIONLevel4Details" xlink:type="simple" xlink:href="ida-20260930.xsd#SEGMENTINFORMATIONLevel4Details"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/SEGMENTINFORMATIONLevel4Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fc884-1cc9-77f1-84da-4653eb11c7d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fc884-1cc9-77f1-84da-4653eb11c7d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fc884-1cc9-7db2-b240-f617d5662f6d" 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_ScheduleOfSegmentReportingInformationBySegmentTable_019fc884-1cc9-77f1-84da-4653eb11c7d5" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fc884-1cc9-7db2-b240-f617d5662f6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fc884-1cc9-7db2-b240-f617d5662f6d_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_019fc884-1cc9-7db2-b240-f617d5662f6d" xlink:to="loc_us-gaap_SegmentDomain_019fc884-1cc9-7db2-b240-f617d5662f6d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fc884-1cc9-7015-bc86-bc36e8d2b296" 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_019fc884-1cc9-7db2-b240-f617d5662f6d" xlink:to="loc_us-gaap_SegmentDomain_019fc884-1cc9-7015-bc86-bc36e8d2b296" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-70ee-90fc-75de2b32c809" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fc884-1cc9-7015-bc86-bc36e8d2b296" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-70ee-90fc-75de2b32c809" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllOtherSegmentsMember_019fc884-1cc9-7733-91cb-6d935a5dbd74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllOtherSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fc884-1cc9-7015-bc86-bc36e8d2b296" xlink:to="loc_us-gaap_AllOtherSegmentsMember_019fc884-1cc9-7733-91cb-6d935a5dbd74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019fc884-1cc9-7be4-ae6b-673313a74911" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fc884-1cc9-77f1-84da-4653eb11c7d5" xlink:to="loc_srt_ConsolidationItemsAxis_019fc884-1cc9-7be4-ae6b-673313a74911" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019fc884-1cc9-7be4-ae6b-673313a74911_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019fc884-1cc9-7be4-ae6b-673313a74911" xlink:to="loc_srt_ConsolidationItemsDomain_019fc884-1cc9-7be4-ae6b-673313a74911_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019fc884-1cc9-761e-82b7-fc2a0f1163f6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019fc884-1cc9-7be4-ae6b-673313a74911" xlink:to="loc_srt_ConsolidationItemsDomain_019fc884-1cc9-761e-82b7-fc2a0f1163f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019fc884-1cc9-78c6-bac1-911d9f88fa38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019fc884-1cc9-761e-82b7-fc2a0f1163f6" xlink:to="loc_us-gaap_OperatingSegmentsMember_019fc884-1cc9-78c6-bac1-911d9f88fa38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationEliminationsMember_019fc884-1cc9-718c-a5c7-4b2fd7a7351d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019fc884-1cc9-761e-82b7-fc2a0f1163f6" xlink:to="loc_srt_ConsolidationEliminationsMember_019fc884-1cc9-718c-a5c7-4b2fd7a7351d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatedAndUnregulatedOperatingRevenue_019fc884-1cc9-7eb7-b7d5-29c4bf87c93d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatedAndUnregulatedOperatingRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_RegulatedAndUnregulatedOperatingRevenue_019fc884-1cc9-7eb7-b7d5-29c4bf87c93d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019fc884-1cc9-788d-84c1-3d54a4ec91f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_Depreciation_019fc884-1cc9-788d-84c1-3d54a4ec91f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OtherIncomeNet_019fc884-1cc9-7eaa-8ca0-c7c344f8fddf" xlink:href="ida-20260930.xsd#ida_OtherIncomeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_ida_OtherIncomeNet_019fc884-1cc9-7eaa-8ca0-c7c344f8fddf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherInterestAndDividendIncome_019fc884-1cc9-7cb7-aa3c-edaa2de23f46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherInterestAndDividendIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_OtherInterestAndDividendIncome_019fc884-1cc9-7cb7-aa3c-edaa2de23f46" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019fc884-1cc9-7bb2-a3c9-c02ff65351ae" 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_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019fc884-1cc9-7bb2-a3c9-c02ff65351ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_019fc884-1cc9-74a1-b6e5-c199fb927efa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_InterestExpense_019fc884-1cc9-74a1-b6e5-c199fb927efa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019fc884-1cc9-745f-a336-10b02dab8a7f" 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_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019fc884-1cc9-745f-a336-10b02dab8a7f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fc884-1cc9-7675-91f8-04ebe768fcdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_NetIncomeLoss_019fc884-1cc9-7675-91f8-04ebe768fcdf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019fc884-1cc9-7e4c-8fd3-891300a2444c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019fc884-1cc9-7e4c-8fd3-891300a2444c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019fc884-1cc9-775b-9b12-7544f34644f6" 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_SegmentReportingInformationLineItems_019fc884-1cc9-73f0-9a58-e6e91d484b15" xlink:to="loc_us-gaap_Assets_019fc884-1cc9-775b-9b12-7544f34644f6" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/CHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMEDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#CHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMEDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/CHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMEDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019fc884-1cc9-7a1a-bfc9-2000804d102c" 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_019fc884-1cc9-76ce-9f64-327c05c73885" 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_019fc884-1cc9-7a1a-bfc9-2000804d102c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019fc884-1cc9-76ce-9f64-327c05c73885" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019fc884-1cc9-7bce-b1a9-5dc29502b905" 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_019fc884-1cc9-76ce-9f64-327c05c73885" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019fc884-1cc9-7bce-b1a9-5dc29502b905" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fc884-1cc9-7bce-b1a9-5dc29502b905_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_019fc884-1cc9-7bce-b1a9-5dc29502b905" xlink:to="loc_us-gaap_EquityComponentDomain_019fc884-1cc9-7bce-b1a9-5dc29502b905_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fc884-1cc9-7acb-8e1a-77acb40a3861" 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_019fc884-1cc9-7bce-b1a9-5dc29502b905" xlink:to="loc_us-gaap_EquityComponentDomain_019fc884-1cc9-7acb-8e1a-77acb40a3861" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019fc884-1cc9-7498-826d-7d42b467233c" 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_EquityComponentDomain_019fc884-1cc9-7acb-8e1a-77acb40a3861" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019fc884-1cc9-7498-826d-7d42b467233c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesAxis_019fc884-1cc9-774b-b210-c86533dbd15a" xlink:href="ida-20260930.xsd#ida_RateCasesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019fc884-1cc9-76ce-9f64-327c05c73885" xlink:to="loc_ida_RateCasesAxis_019fc884-1cc9-774b-b210-c86533dbd15a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc9-774b-b210-c86533dbd15a_default" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc9-774b-b210-c86533dbd15a" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc9-774b-b210-c86533dbd15a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RateCasesDomain_019fc884-1cc9-7dbe-9e83-652c1b1488cd" xlink:href="ida-20260930.xsd#ida_RateCasesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ida_RateCasesAxis_019fc884-1cc9-774b-b210-c86533dbd15a" xlink:to="loc_ida_RateCasesDomain_019fc884-1cc9-7dbe-9e83-652c1b1488cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc9-7230-8715-6222208cca25" xlink:href="ida-20260930.xsd#ida_IdahoPowerCostAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RateCasesDomain_019fc884-1cc9-7dbe-9e83-652c1b1488cd" xlink:to="loc_ida_IdahoPowerCostAdjustmentMember_019fc884-1cc9-7230-8715-6222208cca25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc9-7b74-9675-41ffece24e82" 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_AccumulatedOtherComprehensiveIncomeLossTable_019fc884-1cc9-76ce-9f64-327c05c73885" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc884-1cc9-7b74-9675-41ffece24e82" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc9-7b74-9675-41ffece24e82_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_019fc884-1cc9-7b74-9675-41ffece24e82" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc9-7b74-9675-41ffece24e82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc9-7c11-a0c4-be84faaa1ae5" 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_019fc884-1cc9-7b74-9675-41ffece24e82" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc884-1cc9-7c11-a0c4-be84faaa1ae5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc884-1cc9-7e6d-bc11-775fa6bfad63" 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_019fc884-1cc9-7c11-a0c4-be84faaa1ae5" xlink:to="loc_us-gaap_SubsequentEventMember_019fc884-1cc9-7e6d-bc11-775fa6bfad63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1cc9-75e6-980e-b7b20b10c135" 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_AccumulatedOtherComprehensiveIncomeLossLineItems_019fc884-1cc9-7a1a-bfc9-2000804d102c" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1cc9-75e6-980e-b7b20b10c135" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fc884-1cc9-70f8-937f-dd778636663f" 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_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1cc9-75e6-980e-b7b20b10c135" xlink:to="loc_us-gaap_StockholdersEquity_019fc884-1cc9-70f8-937f-dd778636663f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_019fc884-1cc9-74d8-a7cf-67d9d40da4cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1cc9-75e6-980e-b7b20b10c135" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_019fc884-1cc9-74d8-a7cf-67d9d40da4cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019fc884-1cc9-7e8c-9004-299c73a4f3fb" 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_IncreaseDecreaseInStockholdersEquityRollForward_019fc884-1cc9-75e6-980e-b7b20b10c135" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019fc884-1cc9-7e8c-9004-299c73a4f3fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fc884-1cc9-7c4d-8cc1-f30354a92b5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fc884-1cc9-760d-97cb-feb662d33ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract_019fc884-1cc9-72da-9d51-4da830add6c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019fc884-1cc9-7a1a-bfc9-2000804d102c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract_019fc884-1cc9-72da-9d51-4da830add6c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax_019fc884-1cc9-7d38-9614-a492cfd66f8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract_019fc884-1cc9-72da-9d51-4da830add6c7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax_019fc884-1cc9-7d38-9614-a492cfd66f8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax_019fc884-1cc9-7831-9c82-2be0b56f519a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract_019fc884-1cc9-72da-9d51-4da830add6c7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax_019fc884-1cc9-7831-9c82-2be0b56f519a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax_019fc884-1cc9-7082-9a6a-ba2c5b05d255" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract_019fc884-1cc9-72da-9d51-4da830add6c7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax_019fc884-1cc9-7082-9a6a-ba2c5b05d255" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_019fc884-1cc9-7330-891a-29d221892492" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTaxAbstract_019fc884-1cc9-72da-9d51-4da830add6c7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_019fc884-1cc9-7330-891a-29d221892492" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019fc884-1cc9-7dda-85a8-811b45d77169" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/CHANGESINIDAHOPOWERRETAINEDEARNINGSDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#CHANGESINIDAHOPOWERRETAINEDEARNINGSDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/CHANGESINIDAHOPOWERRETAINEDEARNINGSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ida_ChangesinRetainedEarningsLineItems_019fc884-1cc9-783e-9ace-799efe62cdcb" xlink:href="ida-20260930.xsd#ida_ChangesinRetainedEarningsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_ChangesinRetainedEarningsTable_019fc884-1cc9-74d5-b045-807f26ae5263" xlink:href="ida-20260930.xsd#ida_ChangesinRetainedEarningsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ida_ChangesinRetainedEarningsLineItems_019fc884-1cc9-783e-9ace-799efe62cdcb" xlink:to="loc_ida_ChangesinRetainedEarningsTable_019fc884-1cc9-74d5-b045-807f26ae5263" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc9-7735-9b82-ad2d32595c5a" 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_ida_ChangesinRetainedEarningsTable_019fc884-1cc9-74d5-b045-807f26ae5263" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc9-7735-9b82-ad2d32595c5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-7735-9b82-ad2d32595c5a_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_019fc884-1cc9-7735-9b82-ad2d32595c5a" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-7735-9b82-ad2d32595c5a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-733d-aae9-da031ef64360" 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_019fc884-1cc9-7735-9b82-ad2d32595c5a" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-733d-aae9-da031ef64360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-73fd-85d0-397b395ab063" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc9-733d-aae9-da031ef64360" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-73fd-85d0-397b395ab063" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_RetainedEarningsRollForwardRollForward_019fc884-1cc9-7934-993a-ba0541bbe28e" xlink:href="ida-20260930.xsd#ida_RetainedEarningsRollForwardRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_ChangesinRetainedEarningsLineItems_019fc884-1cc9-783e-9ace-799efe62cdcb" xlink:to="loc_ida_RetainedEarningsRollForwardRollForward_019fc884-1cc9-7934-993a-ba0541bbe28e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019fc884-1cc9-7cb8-93df-6f83a76a1252" 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_ida_RetainedEarningsRollForwardRollForward_019fc884-1cc9-7934-993a-ba0541bbe28e" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019fc884-1cc9-7cb8-93df-6f83a76a1252" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fc884-1cc9-7a2f-89f9-c62e95a71cac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RetainedEarningsRollForwardRollForward_019fc884-1cc9-7934-993a-ba0541bbe28e" xlink:to="loc_us-gaap_NetIncomeLoss_019fc884-1cc9-7a2f-89f9-c62e95a71cac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_019fc884-1cc9-7c31-a971-29d39fbad990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ida_RetainedEarningsRollForwardRollForward_019fc884-1cc9-7934-993a-ba0541bbe28e" xlink:to="loc_us-gaap_Dividends_019fc884-1cc9-7c31-a971-29d39fbad990" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019fc884-1cc9-775c-9f78-9ef226ec8ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.idacorpinc.com/role/ASSETSHELDFORSALEDetails" xlink:type="simple" xlink:href="ida-20260930.xsd#ASSETSHELDFORSALEDetails"/>
  <link:definitionLink xlink:role="http://www.idacorpinc.com/role/ASSETSHELDFORSALEDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019fc884-1cc9-705a-8658-8564a525280a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019fc884-1cc9-705a-8658-8564a525280a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019fc884-1cc9-7e85-8d68-d344716bedb4" 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_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019fc884-1cc9-705a-8658-8564a525280a" xlink:to="loc_dei_LegalEntityAxis_019fc884-1cc9-7e85-8d68-d344716bedb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-7e85-8d68-d344716bedb4_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_019fc884-1cc9-7e85-8d68-d344716bedb4" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-7e85-8d68-d344716bedb4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019fc884-1cc9-7620-98e0-c03e9596a64e" 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_019fc884-1cc9-7e85-8d68-d344716bedb4" xlink:to="loc_dei_EntityDomain_019fc884-1cc9-7620-98e0-c03e9596a64e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-7581-8748-2e6fd11b63f5" xlink:href="ida-20260930.xsd#ida_IdahoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019fc884-1cc9-7620-98e0-c03e9596a64e" xlink:to="loc_ida_IdahoPowerCompanyMember_019fc884-1cc9-7581-8748-2e6fd11b63f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019fc884-1cc9-7dd9-a251-4f353f08cf71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019fc884-1cc9-705a-8658-8564a525280a" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019fc884-1cc9-7dd9-a251-4f353f08cf71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019fc884-1cc9-7dd9-a251-4f353f08cf71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019fc884-1cc9-7dd9-a251-4f353f08cf71" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019fc884-1cc9-7dd9-a251-4f353f08cf71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019fc884-1cc9-789f-b065-e7b572f62fac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019fc884-1cc9-7dd9-a251-4f353f08cf71" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019fc884-1cc9-789f-b065-e7b572f62fac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_019fc884-1cc9-7135-a90f-75ac6db11198" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019fc884-1cc9-789f-b065-e7b572f62fac" xlink:to="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_019fc884-1cc9-7135-a90f-75ac6db11198" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019fc884-1cc9-7300-a9ff-e43d38873ffc" 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_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019fc884-1cc9-705a-8658-8564a525280a" xlink:to="loc_srt_StatementScenarioAxis_019fc884-1cc9-7300-a9ff-e43d38873ffc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc9-7300-a9ff-e43d38873ffc_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_019fc884-1cc9-7300-a9ff-e43d38873ffc" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc9-7300-a9ff-e43d38873ffc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc9-7718-b864-b56d7911c9f7" 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_019fc884-1cc9-7300-a9ff-e43d38873ffc" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019fc884-1cc9-7718-b864-b56d7911c9f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019fc884-1cc9-7461-bb66-1e6394ea6b77" 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_019fc884-1cc9-7718-b864-b56d7911c9f7" xlink:to="loc_srt_ScenarioForecastMember_019fc884-1cc9-7461-bb66-1e6394ea6b77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019fc884-1cc9-7ace-a824-4e13ee3841f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019fc884-1cc9-705a-8658-8564a525280a" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019fc884-1cc9-7ace-a824-4e13ee3841f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019fc884-1cc9-7ace-a824-4e13ee3841f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019fc884-1cc9-7ace-a824-4e13ee3841f1" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019fc884-1cc9-7ace-a824-4e13ee3841f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019fc884-1cc9-7be0-acd1-aa60d7f62fe3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019fc884-1cc9-7ace-a824-4e13ee3841f1" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019fc884-1cc9-7be0-acd1-aa60d7f62fe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_OregonJurisdictionMember_019fc884-1cc9-7952-964c-dc24c7450c55" xlink:href="ida-20260930.xsd#ida_OregonJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019fc884-1cc9-7be0-acd1-aa60d7f62fe3" xlink:to="loc_ida_OregonJurisdictionMember_019fc884-1cc9-7952-964c-dc24c7450c55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_019fc884-1cc9-7b95-aa63-f7e2cfb49226" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_019fc884-1cc9-7b95-aa63-f7e2cfb49226" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf_019fc884-1cc9-7c77-b513-2e5359cdf4e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf_019fc884-1cc9-7c77-b513-2e5359cdf4e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DisposalGroupIncludingDiscontinuedOperationCurrentRegulatoryAssets_019fc884-1cc9-7717-93fa-844344243ebe" xlink:href="ida-20260930.xsd#ida_DisposalGroupIncludingDiscontinuedOperationCurrentRegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_ida_DisposalGroupIncludingDiscontinuedOperationCurrentRegulatoryAssets_019fc884-1cc9-7717-93fa-844344243ebe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment_019fc884-1cc9-7ead-b5d0-bea214054ccf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment_019fc884-1cc9-7ead-b5d0-bea214054ccf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DisposalGroupIncludingDiscontinuedOperationAccumulatedProvisionForDepreciation_019fc884-1cc9-7ac1-89c7-431e4d3163e2" xlink:href="ida-20260930.xsd#ida_DisposalGroupIncludingDiscontinuedOperationAccumulatedProvisionForDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_ida_DisposalGroupIncludingDiscontinuedOperationAccumulatedProvisionForDepreciation_019fc884-1cc9-7ac1-89c7-431e4d3163e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DisposalGroupIncludingDiscontinuedOperationConstructionWorkInProgress_019fc884-1cc9-76d4-a1c1-8fa914c215dd" xlink:href="ida-20260930.xsd#ida_DisposalGroupIncludingDiscontinuedOperationConstructionWorkInProgress"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_ida_DisposalGroupIncludingDiscontinuedOperationConstructionWorkInProgress_019fc884-1cc9-76d4-a1c1-8fa914c215dd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DisposalGroupIncludingDiscontinuedOperationLongTermRegulatoryAssets_019fc884-1cc9-78e6-9430-d6150bda290d" xlink:href="ida-20260930.xsd#ida_DisposalGroupIncludingDiscontinuedOperationLongTermRegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_ida_DisposalGroupIncludingDiscontinuedOperationLongTermRegulatoryAssets_019fc884-1cc9-78e6-9430-d6150bda290d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019fc884-1cc9-795e-8529-bc9a0c12e6d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019fc884-1cc9-795e-8529-bc9a0c12e6d3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DisposalGroupIncludingDiscontinuedOperationCurrentRegulatoryLiabilities_019fc884-1cc9-77a8-9071-8e9ddad11d41" xlink:href="ida-20260930.xsd#ida_DisposalGroupIncludingDiscontinuedOperationCurrentRegulatoryLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_ida_DisposalGroupIncludingDiscontinuedOperationCurrentRegulatoryLiabilities_019fc884-1cc9-77a8-9071-8e9ddad11d41" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ida_DisposalGroupIncludingDiscontinuedOperationLongTermRegulatoryLiabilities_019fc884-1cc9-716d-8b5a-2b2863f4ace8" xlink:href="ida-20260930.xsd#ida_DisposalGroupIncludingDiscontinuedOperationLongTermRegulatoryLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_ida_DisposalGroupIncludingDiscontinuedOperationLongTermRegulatoryLiabilities_019fc884-1cc9-716d-8b5a-2b2863f4ace8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019fc884-1cc9-7c83-961b-3523a660423c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019fc884-1cc9-788e-81ed-29d395329bb8" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019fc884-1cc9-7c83-961b-3523a660423c" xlink:type="arc" order="10"/>
  </link:definitionLink>
</link:linkbase>
