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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f8f21-7b22-7f25-b1cb-330c5357d54d,g:a7d2bd0f-e3d2-49c7-a943-1b2009b6332b-->
<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.seagate.com/role/CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" xlink:type="simple" xlink:href="stx-20260703.xsd#CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f8f21-7d0e-75c6-b9c8-6fb9332250f4" 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_019f8f21-7d0e-77df-bc06-1fe07fcabf4a" 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_019f8f21-7d0e-75c6-b9c8-6fb9332250f4" xlink:to="loc_us-gaap_StatementTable_019f8f21-7d0e-77df-bc06-1fe07fcabf4a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f8f21-7d0e-7404-abef-55edf0792567" 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_019f8f21-7d0e-77df-bc06-1fe07fcabf4a" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f8f21-7d0e-7404-abef-55edf0792567" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7404-abef-55edf0792567_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_019f8f21-7d0e-7404-abef-55edf0792567" xlink:to="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7404-abef-55edf0792567_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7667-958e-6a3164790773" 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_019f8f21-7d0e-7404-abef-55edf0792567" xlink:to="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7667-958e-6a3164790773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f8f21-7d0e-7523-ac9c-1c9ff8403625" 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_019f8f21-7d0e-7667-958e-6a3164790773" xlink:to="loc_us-gaap_CommonStockMember_019f8f21-7d0e-7523-ac9c-1c9ff8403625" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019f8f21-7d0e-7184-9609-821ab2070d06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7667-958e-6a3164790773" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019f8f21-7d0e-7184-9609-821ab2070d06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-7ef8-b582-a125071a955b" 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_019f8f21-7d0e-7667-958e-6a3164790773" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-7ef8-b582-a125071a955b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019f8f21-7d0e-73ab-884e-9373d07807cf" 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_019f8f21-7d0e-7667-958e-6a3164790773" xlink:to="loc_us-gaap_RetainedEarningsMember_019f8f21-7d0e-73ab-884e-9373d07807cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" 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_019f8f21-7d0e-75c6-b9c8-6fb9332250f4" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssued_019f8f21-7d0e-7e3e-a48f-d289d630cb50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_SharesIssued_019f8f21-7d0e-7e3e-a48f-d289d630cb50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f8f21-7d0e-75dd-815e-1c467b36ef0c" 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_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockholdersEquity_019f8f21-7d0e-75dd-815e-1c467b36ef0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7e21-ab58-52d5ad498c86" 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_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7e21-ab58-52d5ad498c86" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f8f21-7d0e-7ab7-9058-e98e621addc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f8f21-7d0e-7ab7-9058-e98e621addc5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_019f8f21-7d0e-7b6e-a7a3-050502857030" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_019f8f21-7d0e-7b6e-a7a3-050502857030" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_019f8f21-7d0e-7df1-b261-ec68e03bed00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_019f8f21-7d0e-7df1-b261-ec68e03bed00" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019f8f21-7d0e-79e1-99c1-cc1841246515" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019f8f21-7d0e-79e1-99c1-cc1841246515" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019f8f21-7d0e-7a94-b17b-1b4a6e609189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019f8f21-7d0e-7a94-b17b-1b4a6e609189" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019f8f21-7d0e-7ded-ab4a-16a10671aede" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019f8f21-7d0e-7ded-ab4a-16a10671aede" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_AdjustmentsToAdditionalPaidInCapitalCappedCallOptionsIssuanceOfConvertibleNotes_019f8f21-7d0e-783b-ad75-e2445f9ceac2" xlink:href="stx-20260703.xsd#stx_AdjustmentsToAdditionalPaidInCapitalCappedCallOptionsIssuanceOfConvertibleNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_stx_AdjustmentsToAdditionalPaidInCapitalCappedCallOptionsIssuanceOfConvertibleNotes_019f8f21-7d0e-783b-ad75-e2445f9ceac2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019f8f21-7d0e-7551-924f-6b6499e228c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019f8f21-7d0e-7551-924f-6b6499e228c7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019f8f21-7d0e-7e49-bbd9-c430dcacf3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019f8f21-7d0e-7e49-bbd9-c430dcacf3ba" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019f8f21-7d0e-7eb7-8514-72a90f824939" 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_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019f8f21-7d0e-7eb7-8514-72a90f824939" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_019f8f21-7d0e-7cd4-98d1-220ac0b81445" 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_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_DividendsCommonStockCash_019f8f21-7d0e-7cd4-98d1-220ac0b81445" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f8f21-7d0e-7b07-a28f-637c9f3fa574" 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_019f8f21-7d0e-75f5-ac0f-2058dad4a6a1" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f8f21-7d0e-7b07-a28f-637c9f3fa574" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssued_019f8f21-7d0e-7218-90e7-74ee38ebb779" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f8f21-7d0e-72f0-88c2-305975780b25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:href="stx-20260703.xsd#stx_ScheduleOfFiscalYearsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:href="stx-20260703.xsd#stx_ScheduleofFiscalYearsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" 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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" 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_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-7816-907f-92d8b8707158" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-7816-907f-92d8b8707158" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f9482-7f0e-70f5-9595-b63fbfadd515" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f9482-7f0e-70f5-9595-b63fbfadd515" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" 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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:href="stx-20260703.xsd#stx_OneCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:href="stx-20260703.xsd#stx_Customer2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:href="stx-20260703.xsd#stx_Customer3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:to="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" 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_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:href="stx-20260703.xsd#stx_EstablishmentOfWarrantyAccrualsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:href="stx-20260703.xsd#stx_ProductWarrantyPeriodTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:to="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:href="stx-20260703.xsd#stx_AdvertisingExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:to="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmountCumulativeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_1" xlink:type="simple" xlink:href="stx-20260703.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:href="stx-20260703.xsd#stx_ScheduleOfFiscalYearsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:href="stx-20260703.xsd#stx_ScheduleofFiscalYearsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" 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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" 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_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" 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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:href="stx-20260703.xsd#stx_OneCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:href="stx-20260703.xsd#stx_Customer2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:href="stx-20260703.xsd#stx_Customer3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:to="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" 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_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:href="stx-20260703.xsd#stx_EstablishmentOfWarrantyAccrualsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:href="stx-20260703.xsd#stx_ProductWarrantyPeriodTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:to="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:href="stx-20260703.xsd#stx_AdvertisingExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:to="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmountCumulativeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_2" xlink:type="simple" xlink:href="stx-20260703.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_2"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:href="stx-20260703.xsd#stx_ScheduleOfFiscalYearsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:href="stx-20260703.xsd#stx_ScheduleofFiscalYearsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" 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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" 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_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" 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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:href="stx-20260703.xsd#stx_OneCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:href="stx-20260703.xsd#stx_Customer2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:href="stx-20260703.xsd#stx_Customer3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:to="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-7816-907f-92d8b8707158" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-7816-907f-92d8b8707158" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" 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_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:href="stx-20260703.xsd#stx_EstablishmentOfWarrantyAccrualsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:href="stx-20260703.xsd#stx_ProductWarrantyPeriodTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:to="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:href="stx-20260703.xsd#stx_AdvertisingExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:to="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmountCumulativeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_3" xlink:type="simple" xlink:href="stx-20260703.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_3"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:href="stx-20260703.xsd#stx_ScheduleOfFiscalYearsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:href="stx-20260703.xsd#stx_ScheduleofFiscalYearsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7d59-8bac-2194a2f7894b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" 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_019f8f21-7d0e-7d59-8bac-2194a2f7894b" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7179-a7eb-c76d76e87a3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" 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_019f8f21-7d0e-7093-ac6d-bfe4d91792a7" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7abe-b8f5-2411f3bae276" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-7d1c-821e-e097d7b4ff48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GovernmentAssistanceTypeAxis_019f8f21-7d0e-7d1c-821e-e097d7b4ff48" xlink:to="loc_us-gaap_GovernmentAssistanceTypeDomain_019f8f21-7d0e-74bd-b92e-d558f311e7e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_srt_MajorCustomersAxis_019f9596-09d3-7452-807b-dcc3acbee358" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7452-807b-dcc3acbee358_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" 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_019f9596-09d3-7452-807b-dcc3acbee358" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:href="stx-20260703.xsd#stx_OneCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_OneCustomerMember_019f9596-09d3-7015-995a-477a236c089b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:href="stx-20260703.xsd#stx_Customer2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer2Member_019f9596-09d3-78f2-aac3-92da41f15026" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:href="stx-20260703.xsd#stx_Customer3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f9596-09d3-7f3a-8c68-b0b76f424517" xlink:to="loc_stx_Customer3Member_019f9596-09d3-7b78-b326-98d762f4f456" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-74f4-8c1c-595f0984c8cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f9596-09d3-74f4-8c1c-595f0984c8cf" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f9596-09d3-7b4c-9265-de7b169f03b4" xlink:to="loc_us-gaap_AccountsReceivableMember_019f9596-09d3-7e8f-b62c-43c64244ef02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-702d-95d7-9b3039b254c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f9596-09d3-702d-95d7-9b3039b254c5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019f9596-09d3-753b-9d9b-16d91e87f757" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019f9596-09d3-71a9-afef-636ae1b5a6f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f9482-7f0e-70f5-9595-b63fbfadd515" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7d0e-7e84-844f-8f4a52349725" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f9482-7f0e-70f5-9595-b63fbfadd515" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" 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_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_NetIncomeLoss_019f8f21-7d0e-7bac-b8ea-882903b40d10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019f8f21-7d0e-7dc0-aa8a-ae3b7f72a990" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:href="stx-20260703.xsd#stx_EstablishmentOfWarrantyAccrualsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:href="stx-20260703.xsd#stx_ProductWarrantyPeriodTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_EstablishmentOfWarrantyAccrualsAbstract_019f8f21-7d0e-74bb-bae5-5a0ec948eb71" xlink:to="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7d0e-74b4-b589-defaae83ffc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:href="stx-20260703.xsd#stx_AdvertisingExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AdvertisingExpenseAbstract_019f8f21-7d0e-7c76-a4f6-c76ef0fa2c32" xlink:to="loc_us-gaap_AdvertisingExpense_019f8f21-7d0e-7072-815a-e8dea24d2328" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmount_019f8f21-7d0e-7663-a4f3-21df32521ff5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-70e7-aa4c-9f7ae30545ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_019f8f21-7d0e-7e56-a43f-cf4159bd3bd3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAmountCumulativeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAmountCumulativeCurrent_019f8f21-7d0e-7621-bbbf-3868f88b934d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceCurrentStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d57-8449-682a00406482" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecrease_019f8f21-7d0e-744e-91ee-f9d5817c0401" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_GovernmentAssistanceAssetDecreaseStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7d0e-7d2b-ad17-d43f5ee5bd57" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7d0e-7cf8-b6d4-73a874cb6462" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f9596-09d3-7f09-a713-9ad370c0d8e6" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BalanceSheetInformationNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#BalanceSheetInformationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BalanceSheetInformationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-7c2e-83f9-c8e80fdae47b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-7c2e-83f9-c8e80fdae47b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-7664-807c-ac2a9eff12bf" 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_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-7c2e-83f9-c8e80fdae47b" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-7664-807c-ac2a9eff12bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_019f8f21-7d0e-7079-b46c-5498e1aa8965" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_019f8f21-7d0e-7079-b46c-5498e1aa8965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsDerecognizedAmount_019f8f21-7d0e-721c-a96d-c9e6d32bd14c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsDerecognizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsDerecognizedAmount_019f8f21-7d0e-721c-a96d-c9e6d32bd14c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding_019f8f21-7d0e-7032-afb8-1bedd7f28bbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding_019f8f21-7d0e-7032-afb8-1bedd7f28bbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ContinuingInvolvementWithContinuedToBeRecognizedTransferredFinancialAssetsDiscount_019f8f21-7d0e-75ee-bb9b-b75812809d6e" xlink:href="stx-20260703.xsd#stx_ContinuingInvolvementWithContinuedToBeRecognizedTransferredFinancialAssetsDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_stx_ContinuingInvolvementWithContinuedToBeRecognizedTransferredFinancialAssetsDiscount_019f8f21-7d0e-75ee-bb9b-b75812809d6e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019f8f21-7d0e-79ea-8812-82850767f10a" 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_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_Depreciation_019f8f21-7d0e-79ea-8812-82850767f10a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestCostsCapitalized_019f8f21-7d0e-7097-a600-d6ba961c24d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestCostsCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_InterestCostsCapitalized_019f8f21-7d0e-7097-a600-d6ba961c24d0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BalanceSheetInformationNarrativeDetails_1" xlink:type="simple" xlink:href="stx-20260703.xsd#BalanceSheetInformationNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BalanceSheetInformationNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-7c2e-83f9-c8e80fdae47b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-7c2e-83f9-c8e80fdae47b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_019f8f21-7d0e-7079-b46c-5498e1aa8965" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_019f8f21-7d0e-7079-b46c-5498e1aa8965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsDerecognizedAmount_019f8f21-7d0e-721c-a96d-c9e6d32bd14c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsDerecognizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsDerecognizedAmount_019f8f21-7d0e-721c-a96d-c9e6d32bd14c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding_019f8f21-7d0e-7032-afb8-1bedd7f28bbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding_019f8f21-7d0e-7032-afb8-1bedd7f28bbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ContinuingInvolvementWithContinuedToBeRecognizedTransferredFinancialAssetsDiscount_019f8f21-7d0e-75ee-bb9b-b75812809d6e" xlink:href="stx-20260703.xsd#stx_ContinuingInvolvementWithContinuedToBeRecognizedTransferredFinancialAssetsDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_stx_ContinuingInvolvementWithContinuedToBeRecognizedTransferredFinancialAssetsDiscount_019f8f21-7d0e-75ee-bb9b-b75812809d6e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019f8f21-7d0e-79ea-8812-82850767f10a" 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_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_Depreciation_019f8f21-7d0e-79ea-8812-82850767f10a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestCostsCapitalized_019f8f21-7d0e-7097-a600-d6ba961c24d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestCostsCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-779e-afd2-893b9662bf4f" xlink:to="loc_us-gaap_InterestCostsCapitalized_019f8f21-7d0e-7097-a600-d6ba961c24d0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BalanceSheetInformationPropertyEquipmentandLeaseholdImprovementsnetDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#BalanceSheetInformationPropertyEquipmentandLeaseholdImprovementsnetDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BalanceSheetInformationPropertyEquipmentandLeaseholdImprovementsnetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-7ab8-b455-a70b41617c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-74fc-befd-6dbc2e6391aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-7ab8-b455-a70b41617c94" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-74fc-befd-6dbc2e6391aa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f8f21-7d0e-7043-acb9-1a7c6ed6427a" 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_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-74fc-befd-6dbc2e6391aa" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f8f21-7d0e-7043-acb9-1a7c6ed6427a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7043-acb9-1a7c6ed6427a_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_019f8f21-7d0e-7043-acb9-1a7c6ed6427a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7043-acb9-1a7c6ed6427a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7a1c-8fb0-8f8acab93a18" 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_019f8f21-7d0e-7043-acb9-1a7c6ed6427a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7a1c-8fb0-8f8acab93a18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_019f8f21-7d0e-76cd-9991-5b13a7b78a1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7a1c-8fb0-8f8acab93a18" xlink:to="loc_us-gaap_LandMember_019f8f21-7d0e-76cd-9991-5b13a7b78a1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_019f8f21-7d0e-7d6e-be87-42d7659bab77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7a1c-8fb0-8f8acab93a18" xlink:to="loc_us-gaap_EquipmentMember_019f8f21-7d0e-7d6e-be87-42d7659bab77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_BuildingAndLeaseholdImprovementsMember_019f8f21-7d0e-715e-8791-fbd0cfa4c9bf" xlink:href="stx-20260703.xsd#stx_BuildingAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7a1c-8fb0-8f8acab93a18" xlink:to="loc_stx_BuildingAndLeaseholdImprovementsMember_019f8f21-7d0e-715e-8791-fbd0cfa4c9bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_019f8f21-7d0e-73d1-9505-528d234653ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f8f21-7d0e-7a1c-8fb0-8f8acab93a18" xlink:to="loc_us-gaap_ConstructionInProgressMember_019f8f21-7d0e-73d1-9505-528d234653ca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-7cd3-9464-2f13b034d661" 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_ScheduleOfPropertyPlantAndEquipmentTable_019f8f21-7d0e-74fc-befd-6dbc2e6391aa" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-7cd3-9464-2f13b034d661" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7cd3-9464-2f13b034d661_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_019f8f21-7d0e-7cd3-9464-2f13b034d661" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7cd3-9464-2f13b034d661_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-79d9-b276-b7d1f90ef539" 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_019f8f21-7d0e-7cd3-9464-2f13b034d661" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-79d9-b276-b7d1f90ef539" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7e9b-8b17-d6fc9687f9ba" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-79d9-b276-b7d1f90ef539" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7e9b-8b17-d6fc9687f9ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7ff4-bc74-1e6e1188394e" 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_019f8f21-7d0e-79d9-b276-b7d1f90ef539" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7ff4-bc74-1e6e1188394e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-7b8d-b534-dc87036a7055" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-7ab8-b455-a70b41617c94" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f8f21-7d0e-7b8d-b534-dc87036a7055" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019f8f21-7d0e-7c82-bbad-c93836037636" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-7ab8-b455-a70b41617c94" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019f8f21-7d0e-7c82-bbad-c93836037636" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019f8f21-7d0e-71f6-bfc1-74744791356a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-7ab8-b455-a70b41617c94" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019f8f21-7d0e-71f6-bfc1-74744791356a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019f8f21-7d0e-7a19-8283-947b6b3a9adc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f8f21-7d0e-7ab8-b455-a70b41617c94" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019f8f21-7d0e-7a19-8283-947b6b3a9adc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BalanceSheetInformationAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#BalanceSheetInformationAccumulatedOtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BalanceSheetInformationAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019f8f21-7d0e-7c8f-af65-f2b14d12f193" 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_019f8f21-7d0e-7591-bdb6-f739b9a16f35" 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_019f8f21-7d0e-7c8f-af65-f2b14d12f193" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019f8f21-7d0e-7591-bdb6-f739b9a16f35" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f8f21-7d0e-7a8a-85d1-2c4928681417" 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_019f8f21-7d0e-7591-bdb6-f739b9a16f35" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f8f21-7d0e-7a8a-85d1-2c4928681417" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7a8a-85d1-2c4928681417_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_019f8f21-7d0e-7a8a-85d1-2c4928681417" xlink:to="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7a8a-85d1-2c4928681417_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7a6c-b716-51e802c3b0b8" 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_019f8f21-7d0e-7a8a-85d1-2c4928681417" xlink:to="loc_us-gaap_EquityComponentDomain_019f8f21-7d0e-7a6c-b716-51e802c3b0b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-789b-b22d-3726e8d7da1f" 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_019f8f21-7d0e-7a6c-b716-51e802c3b0b8" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-789b-b22d-3726e8d7da1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019f8f21-7d0e-7b2f-9031-519e9a182f76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-789b-b22d-3726e8d7da1f" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019f8f21-7d0e-7b2f-9031-519e9a182f76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_019f8f21-7d0e-78c5-b835-91112b658840" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-789b-b22d-3726e8d7da1f" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_019f8f21-7d0e-78c5-b835-91112b658840" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f8f21-7d0e-7ba7-812b-b71c09d99e78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f8f21-7d0e-789b-b22d-3726e8d7da1f" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f8f21-7d0e-7ba7-812b-b71c09d99e78" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:href="stx-20260703.xsd#stx_AccumulatedOtherComprehensiveIncomeLossRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019f8f21-7d0e-7c8f-af65-f2b14d12f193" xlink:to="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f8f21-7d0e-709f-a9f2-3e089d9d3812" 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_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_StockholdersEquity_019f8f21-7d0e-709f-a9f2-3e089d9d3812" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax_019f8f21-7d0e-7c7f-be72-aebbcee8adf6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax_019f8f21-7d0e-7c7f-be72-aebbcee8adf6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_019f8f21-7d0e-7009-be62-0a45541bdca1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_019f8f21-7d0e-7009-be62-0a45541bdca1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_019f8f21-7d0e-7839-a04f-93e206e25331" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_019f8f21-7d0e-7839-a04f-93e206e25331" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019f8f21-7d0e-7cb6-9e81-bc93ed0187ff" 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_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_019f8f21-7d0e-7cb6-9e81-bc93ed0187ff" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_019f8f21-7d0e-7ce4-beec-27e6e0d81f54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_019f8f21-7d0e-7ce4-beec-27e6e0d81f54" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax_019f8f21-7d0e-7697-83c6-73cc2e2e348f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax_019f8f21-7d0e-7697-83c6-73cc2e2e348f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_019f8f21-7d0e-70e3-8950-5e624bff00a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_019f8f21-7d0e-70e3-8950-5e624bff00a5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_019f8f21-7d0e-79b7-bad5-e59c2cd36378" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_019f8f21-7d0e-79b7-bad5-e59c2cd36378" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019f8f21-7d0e-78a2-9f04-63a59a9939d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019f8f21-7d0e-78a2-9f04-63a59a9939d5" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019f8f21-7d0e-72cf-b1ab-2fc3d42fede2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_AccumulatedOtherComprehensiveIncomeLossRollForward_019f8f21-7d0e-7993-9fbd-2fe649b3f185" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019f8f21-7d0e-72cf-b1ab-2fc3d42fede2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f8f21-7d0e-7814-b182-1fb2cbd5bee5" 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_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019f902e-c06b-7e61-8abf-70702f5e6e21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019f8f21-7d0e-7c8f-af65-f2b14d12f193" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019f902e-c06b-7e61-8abf-70702f5e6e21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_019f902e-c06b-75fe-b2f4-3e0a4b037552" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019f8f21-7d0e-7c8f-af65-f2b14d12f193" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_019f902e-c06b-75fe-b2f4-3e0a4b037552" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/GoodwillandOtherIntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#GoodwillandOtherIntangibleAssetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/GoodwillandOtherIntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019f8f21-7d0e-7618-a033-9ccb5aeecded" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019f8f21-7d0e-7618-a033-9ccb5aeecded" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019f8f21-7d0e-7604-b684-40d230203f63" 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_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019f8f21-7d0e-7618-a033-9ccb5aeecded" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019f8f21-7d0e-7604-b684-40d230203f63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7d0e-7604-b684-40d230203f63_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_019f8f21-7d0e-7604-b684-40d230203f63" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7d0e-7604-b684-40d230203f63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7d0e-7f08-83db-7f6cbd120a6f" 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_019f8f21-7d0e-7604-b684-40d230203f63" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7d0e-7f08-83db-7f6cbd120a6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019f8f21-7d0e-796a-9d41-9d1c10ae3dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7d0e-7f08-83db-7f6cbd120a6f" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019f8f21-7d0e-796a-9d41-9d1c10ae3dd1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7d0e-7ac7-933c-b1fb0f29f930" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019f8f21-7d0e-7618-a033-9ccb5aeecded" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7d0e-7ac7-933c-b1fb0f29f930" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7d0e-7ac7-933c-b1fb0f29f930_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7d0e-7ac7-933c-b1fb0f29f930" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7d0e-7ac7-933c-b1fb0f29f930_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7d0e-787a-afde-bfeb3b62e9b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7d0e-7ac7-933c-b1fb0f29f930" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7d0e-787a-afde-bfeb3b62e9b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_IntevacInc.Member_019f8f21-7d0e-79d4-a3db-a6c9614ffc96" xlink:href="stx-20260703.xsd#stx_IntevacInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7d0e-787a-afde-bfeb3b62e9b2" xlink:to="loc_stx_IntevacInc.Member_019f8f21-7d0e-79d4-a3db-a6c9614ffc96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f8f21-7d0e-7bf7-84fa-6713c96e7a63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_Goodwill_019f8f21-7d0e-7bf7-84fa-6713c96e7a63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019f8f21-7d0e-7d4e-abd3-a7c7f94a5b28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019f8f21-7d0e-7d4e-abd3-a7c7f94a5b28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019f8f21-7d0e-7315-840e-407419ea251e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019f8f21-7d0e-7315-840e-407419ea251e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill1_019f8f21-7d0e-7b26-babc-f5d80f8c2806" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill1_019f8f21-7d0e-7b26-babc-f5d80f8c2806" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019f8f21-7d0e-775e-8825-ced7cebf4b77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019f8f21-7d0e-775e-8825-ced7cebf4b77" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019f8f21-7d0e-76e1-a285-cac264657f53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019f8f21-7d0e-76e1-a285-cac264657f53" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019f8f21-7d0e-7445-8dfe-ac67db15a6fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019f8f21-7d0e-7bcf-acbc-c0f7c0280137" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019f8f21-7d0e-7445-8dfe-ac67db15a6fd" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/DebtLongtermDebtDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#DebtLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/DebtLongtermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" 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_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" 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_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-7ad6-b16e-b86ace742d3d" 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_DebtInstrumentTable_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-7ad6-b16e-b86ace742d3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7ad6-b16e-b86ace742d3d_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_019f8f21-7d0e-7ad6-b16e-b86ace742d3d" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7ad6-b16e-b86ace742d3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7faf-9f6e-15001fdb9ed2" 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_019f8f21-7d0e-7ad6-b16e-b86ace742d3d" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7faf-9f6e-15001fdb9ed2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-776c-93db-ef3b7c6101a4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7faf-9f6e-15001fdb9ed2" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-776c-93db-ef3b7c6101a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7dee-b15f-4efff18f2104" 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_019f8f21-7d0e-7faf-9f6e-15001fdb9ed2" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7dee-b15f-4efff18f2104" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f8f21-7d0e-73ac-a2d4-002461e788b1" 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_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f8f21-7d0e-73ac-a2d4-002461e788b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-73ac-a2d4-002461e788b1_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_019f8f21-7d0e-73ac-a2d4-002461e788b1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-73ac-a2d4-002461e788b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7194-9cee-3a2d18c88bca" 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_019f8f21-7d0e-73ac-a2d4-002461e788b1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7194-9cee-3a2d18c88bca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f8f21-7d0e-7ce6-8c5f-457ee6fae020" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7194-9cee-3a2d18c88bca" xlink:to="loc_us-gaap_SeniorNotesMember_019f8f21-7d0e-7ce6-8c5f-457ee6fae020" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_019f8f21-7d0e-7f28-8a01-6a95c0bc1d14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7194-9cee-3a2d18c88bca" xlink:to="loc_us-gaap_ConvertibleDebtMember_019f8f21-7d0e-7f28-8a01-6a95c0bc1d14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_UnsecuredSeniorNotesIssuedBySeagateHDDCaymanMember_019f8f21-7d0e-7d2f-940f-f5e6539c6802" xlink:href="stx-20260703.xsd#stx_UnsecuredSeniorNotesIssuedBySeagateHDDCaymanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7194-9cee-3a2d18c88bca" xlink:to="loc_stx_UnsecuredSeniorNotesIssuedBySeagateHDDCaymanMember_019f8f21-7d0e-7d2f-940f-f5e6539c6802" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_UnsecuredSeniorNotesIssuedBySeagateDataStorageTechnologyPte.LtdMember_019f8f21-7d0e-7bd0-93b9-ba9be8102320" xlink:href="stx-20260703.xsd#stx_UnsecuredSeniorNotesIssuedBySeagateDataStorageTechnologyPte.LtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7194-9cee-3a2d18c88bca" xlink:to="loc_stx_UnsecuredSeniorNotesIssuedBySeagateDataStorageTechnologyPte.LtdMember_019f8f21-7d0e-7bd0-93b9-ba9be8102320" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7a8e-916b-1892ed196235" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7a8e-916b-1892ed196235" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a8e-916b-1892ed196235_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7a8e-916b-1892ed196235" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a8e-916b-1892ed196235_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7a8e-916b-1892ed196235" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-76a6-83ac-38a3c9ab7826" xlink:href="stx-20260703.xsd#stx_SeniorNotes4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-76a6-83ac-38a3c9ab7826" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20291Member_019f8f21-7d0e-7193-a3da-cc05f7ec7cb9" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20291Member_019f8f21-7d0e-7193-a3da-cc05f7ec7cb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-7075-9bd3-9573590c6edf" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-7075-9bd3-9573590c6edf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-78a8-8f18-e760adecd7cd" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-78a8-8f18-e760adecd7cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Seniornote5.75percentdueDecember2034Member_019f8f21-7d0e-7144-947b-33b1ed122648" xlink:href="stx-20260703.xsd#stx_Seniornote5.75percentdueDecember2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_Seniornote5.75percentdueDecember2034Member_019f8f21-7d0e-7144-947b-33b1ed122648" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-7e58-bf07-09a8d8656120" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-7e58-bf07-09a8d8656120" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-7ee7-8a3d-af6c90f345af" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-7ee7-8a3d-af6c90f345af" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7f47-8a5f-af94e3876253" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7f47-8a5f-af94e3876253" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7d0e-70ad-ba6e-0395e47d4b37" xlink:href="stx-20260703.xsd#stx_ConvertibleSeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7d0e-70ad-ba6e-0395e47d4b37" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes5.875PercentDueJuly2030Member_019f8f21-7d0e-74e0-9208-6c9956e89bcd" xlink:href="stx-20260703.xsd#stx_SeniorNotes5.875PercentDueJuly2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes5.875PercentDueJuly2030Member_019f8f21-7d0e-74e0-9208-6c9956e89bcd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNote4091PercentDueJune2029Member_019f904e-8132-7c35-be35-209f5d5367da" xlink:href="stx-20260703.xsd#stx_SeniorNote4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNote4091PercentDueJune2029Member_019f904e-8132-7c35-be35-209f5d5367da" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019f904f-542f-74d1-918a-e325c7dec585" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019f904f-542f-74d1-918a-e325c7dec585" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20322Member_019f9050-06c1-72c1-a9f3-4774a83cc1a3" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20322Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20322Member_019f9050-06c1-72c1-a9f3-4774a83cc1a3" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019f905b-28d5-7da8-921b-874bbba222cf" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20292Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019f905b-28d5-7da8-921b-874bbba222cf" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20292Member_019f905f-27bd-7aed-abe3-9725eac5bf3c" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20292Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7d7a-a37e-d20986e35a46" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20292Member_019f905f-27bd-7aed-abe3-9725eac5bf3c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019f8f21-7d0e-7343-83bc-94875653b47c" 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_DebtInstrumentTable_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019f8f21-7d0e-7343-83bc-94875653b47c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7d0e-7343-83bc-94875653b47c_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_019f8f21-7d0e-7343-83bc-94875653b47c" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7d0e-7343-83bc-94875653b47c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019f8f21-7d0e-7db8-ab17-bada26716a3a" 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_019f8f21-7d0e-7343-83bc-94875653b47c" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019f8f21-7d0e-7db8-ab17-bada26716a3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7d0e-7605-99f8-d786ab6e6579" 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_019f8f21-7d0e-7db8-ab17-bada26716a3a" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7d0e-7605-99f8-d786ab6e6579" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019f8f21-7d0e-7271-abce-ea10921a8ea7" 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_PortionAtFairValueFairValueDisclosureMember_019f8f21-7d0e-7605-99f8-d786ab6e6579" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019f8f21-7d0e-7271-abce-ea10921a8ea7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-70ae-99d6-11939915a3b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7be9-b61a-5ea4e0e4a17b" xlink:to="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-70ae-99d6-11939915a3b6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-70ae-99d6-11939915a3b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-70ae-99d6-11939915a3b6" xlink:to="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-70ae-99d6-11939915a3b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-7dc9-904b-9a8d0e11e186" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-70ae-99d6-11939915a3b6" xlink:to="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-7dc9-904b-9a8d0e11e186" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MediumTermNotesMember_019f8f21-7d0e-7fbb-95d6-1f8767eff75d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MediumTermNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-7dc9-904b-9a8d0e11e186" xlink:to="loc_us-gaap_MediumTermNotesMember_019f8f21-7d0e-7fbb-95d6-1f8767eff75d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotes_019f8f21-7d0e-725f-abd2-6dcefc6786e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_SeniorNotes_019f8f21-7d0e-725f-abd2-6dcefc6786e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-72af-b8df-f033b504a5bb" 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_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-72af-b8df-f033b504a5bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-7419-b81b-778ee02b4fe5" 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_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-7419-b81b-778ee02b4fe5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019f8f21-7d0e-7eca-b4d8-12a7ca0e6ff1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019f8f21-7d0e-7eca-b4d8-12a7ca0e6ff1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019f8f21-7d0e-73ff-b495-daba1d8165eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019f8f21-7d0e-73ff-b495-daba1d8165eb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f8f21-7d0e-74a6-b7ed-340a12c259c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_LongTermDebt_019f8f21-7d0e-74a6-b7ed-340a12c259c9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019f8f21-7d0e-717a-b33e-afafe40c53f3" 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_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_LongTermDebtCurrent_019f8f21-7d0e-717a-b33e-afafe40c53f3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019f8f21-7d0e-78c1-b360-9ef2ffc94b59" 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_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019f8f21-7d0e-78c1-b360-9ef2ffc94b59" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f8f21-7d0e-703e-991b-e809bc116a67" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f8f21-7d0e-703e-991b-e809bc116a67" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebt_019f8f21-7d0e-7d58-bfb7-1fccd6d6ec9a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7087-a36f-c0af731e9818" xlink:to="loc_us-gaap_ConvertibleDebt_019f8f21-7d0e-7d58-bfb7-1fccd6d6ec9a" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" 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_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" 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_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f8f21-7d0e-70ba-adc3-81b8840c863d" 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_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f8f21-7d0e-70ba-adc3-81b8840c863d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-70ba-adc3-81b8840c863d_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_019f8f21-7d0e-70ba-adc3-81b8840c863d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-70ba-adc3-81b8840c863d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" 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_019f8f21-7d0e-70ba-adc3-81b8840c863d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f8f21-7d0e-75ea-8c84-dcafa352452d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_us-gaap_SeniorNotesMember_019f8f21-7d0e-75ea-8c84-dcafa352452d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-7878-82a6-a71dcf428d6f" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-7878-82a6-a71dcf428d6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-791f-aae2-41ca6544a114" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-791f-aae2-41ca6544a114" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7985-82ef-9624f8475394" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7985-82ef-9624f8475394" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_TermsLoansA1A2AndA3Member_019f8f21-7d0e-7ce9-8d01-59fc6dc39f15" xlink:href="stx-20260703.xsd#stx_TermsLoansA1A2AndA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_TermsLoansA1A2AndA3Member_019f8f21-7d0e-7ce9-8d01-59fc6dc39f15" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_019f8f21-7d0e-7f3a-90de-8357275eb6a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_us-gaap_ConvertibleDebtMember_019f8f21-7d0e-7f3a-90de-8357275eb6a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorUnsecuredRevolvingCreditFacilityMember_019f8f21-7d0e-7e36-a117-18fbd3564c69" xlink:href="stx-20260703.xsd#stx_SeniorUnsecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorUnsecuredRevolvingCreditFacilityMember_019f8f21-7d0e-7e36-a117-18fbd3564c69" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NewCreditAgreementMember_019f8f21-7d0e-795b-b9eb-90c3430ed75b" xlink:href="stx-20260703.xsd#stx_NewCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_NewCreditAgreementMember_019f8f21-7d0e-795b-b9eb-90c3430ed75b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7566-b91a-6b7b13beb872_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7566-b91a-6b7b13beb872_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-7721-96a6-7eceea175127" xlink:href="stx-20260703.xsd#stx_SeniorNotes4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-7721-96a6-7eceea175127" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-74ed-80b9-30672465b6c6" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-74ed-80b9-30672465b6c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-73cd-89b6-32078a5f6de2" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-73cd-89b6-32078a5f6de2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-785d-bad6-ce827b9fe656" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-785d-bad6-ce827b9fe656" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-754f-b5e9-a825ba1e58ea" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-754f-b5e9-a825ba1e58ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNote350PercentDueJune2028Member_019f8f21-7d0e-7361-9237-44325afac286" xlink:href="stx-20260703.xsd#stx_SeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNote350PercentDueJune2028Member_019f8f21-7d0e-7361-9237-44325afac286" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7d0e-74bc-a7ac-9997ca7df16b" xlink:href="stx-20260703.xsd#stx_ConvertibleSeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7d0e-74bc-a7ac-9997ca7df16b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f8f21-7d0e-7de6-abab-c3072733c237" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f8f21-7d0e-7de6-abab-c3072733c237" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019faaf1-64e9-74ae-8c42-b5405efb7969" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20292Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019faaf1-64e9-74ae-8c42-b5405efb7969" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019faaf1-64e9-7fd3-a1a6-ce6c86cac0ea" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019faaf1-64e9-7fd3-a1a6-ce6c86cac0ea" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20312Member_019faaf3-623c-77d8-a66a-60b5ba0e3f83" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20312Member_019faaf3-623c-77d8-a66a-60b5ba0e3f83" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-71bf-9801-378cc4d14e62_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:to="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-71bf-9801-378cc4d14e62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:to="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MediumTermNotesMember_019f8f21-7d0e-70c4-9933-a77246a1b5db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MediumTermNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:to="loc_us-gaap_MediumTermNotesMember_019f8f21-7d0e-70c4-9933-a77246a1b5db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019f8f21-7d0e-74e4-a673-7aa5c5b3dba5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:to="loc_us-gaap_LetterOfCreditMember_019f8f21-7d0e-74e4-a673-7aa5c5b3dba5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SwingLineLoansMember_019f8f21-7d0e-7ea2-9956-54154e86258e" xlink:href="stx-20260703.xsd#stx_SwingLineLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:to="loc_stx_SwingLineLoansMember_019f8f21-7d0e-7ea2-9956-54154e86258e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-76ab-8d78-1f89cb97616d" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-76ab-8d78-1f89cb97616d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-76ab-8d78-1f89cb97616d_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_019f8f21-7d0e-76ab-8d78-1f89cb97616d" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-76ab-8d78-1f89cb97616d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7522-aff9-3ad0d875189c" 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_019f8f21-7d0e-76ab-8d78-1f89cb97616d" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7522-aff9-3ad0d875189c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7661-bc37-6f0cf881b62d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7522-aff9-3ad0d875189c" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7661-bc37-6f0cf881b62d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7547-94c5-5c2022927b3c" 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_019f8f21-7d0e-7522-aff9-3ad0d875189c" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7547-94c5-5c2022927b3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-73d7-b8a5-e891260fbf41" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7d0e-73d7-b8a5-e891260fbf41" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019f8f21-7d0e-7751-a077-c11b2d1976a9" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_srt_StatementScenarioAxis_019f8f21-7d0e-7751-a077-c11b2d1976a9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-7751-a077-c11b2d1976a9_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_019f8f21-7d0e-7751-a077-c11b2d1976a9" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-7751-a077-c11b2d1976a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-788e-96fb-9b3c47df59ea" 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_019f8f21-7d0e-7751-a077-c11b2d1976a9" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-788e-96fb-9b3c47df59ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019f8f21-7d0e-7595-b4d3-25c7cf07c9fb" 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_019f8f21-7d0e-788e-96fb-9b3c47df59ea" xlink:to="loc_srt_ScenarioForecastMember_019f8f21-7d0e-7595-b4d3-25c7cf07c9fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f8f21-7d0e-7e4a-9034-c89515ad75d5" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f8f21-7d0e-7e4a-9034-c89515ad75d5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7e4a-9034-c89515ad75d5_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_019f8f21-7d0e-7e4a-9034-c89515ad75d5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7e4a-9034-c89515ad75d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7d3d-8d59-27197cc15a15" 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_019f8f21-7d0e-7e4a-9034-c89515ad75d5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7d3d-8d59-27197cc15a15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019f8f21-7d0e-75fa-96e5-40b7a67d461e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7d3d-8d59-27197cc15a15" xlink:to="loc_us-gaap_InterestRateSwapMember_019f8f21-7d0e-75fa-96e5-40b7a67d461e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019faaf5-d6dc-7c60-b609-70e8163acccd" 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_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019faaf5-d6dc-7c60-b609-70e8163acccd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-7c60-b609-70e8163acccd_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_019faaf5-d6dc-7c60-b609-70e8163acccd" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-7c60-b609-70e8163acccd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-77e6-8120-06315413a5e4" 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_019faaf5-d6dc-7c60-b609-70e8163acccd" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-77e6-8120-06315413a5e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019faaf5-f1ca-7e6a-a796-73efe2a68c23" 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_019faaf5-d6dc-77e6-8120-06315413a5e4" xlink:to="loc_us-gaap_SubsequentEventMember_019faaf5-f1ca-7e6a-a796-73efe2a68c23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-76e3-a22e-45cb79f9bef1" 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_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-76e3-a22e-45cb79f9bef1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-7ea6-8ed3-1d23db9313e3" 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_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-7ea6-8ed3-1d23db9313e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f8f21-7d0e-746e-b35d-aebf42d11487" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f8f21-7d0e-746e-b35d-aebf42d11487" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnRepurchaseOfDebtInstrument_019f8f21-7d0e-7632-a0eb-7c5b550bc7e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnRepurchaseOfDebtInstrument"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_GainLossOnRepurchaseOfDebtInstrument_019f8f21-7d0e-7632-a0eb-7c5b550bc7e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentCovenantLeverageRatioMaximum_019f8f21-7d0e-77f7-b3e0-a2e25e1b4e25" xlink:href="stx-20260703.xsd#stx_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentCovenantLeverageRatioMaximum_019f8f21-7d0e-77f7-b3e0-a2e25e1b4e25" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentOverAllotmentOptionAmount_019f8f21-7d0e-7b38-889f-abdc5420d913" xlink:href="stx-20260703.xsd#stx_DebtInstrumentOverAllotmentOptionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentOverAllotmentOptionAmount_019f8f21-7d0e-7b38-889f-abdc5420d913" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_CappedCallTransactionPricePerShare_019f8f21-7d0e-77ad-bd95-c0f52ab8c4a8" xlink:href="stx-20260703.xsd#stx_CappedCallTransactionPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_CappedCallTransactionPricePerShare_019f8f21-7d0e-77ad-bd95-c0f52ab8c4a8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019f8f21-7d0e-74d6-9dfc-92c061640f45" 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_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_InterestExpenseDebt_019f8f21-7d0e-74d6-9dfc-92c061640f45" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f8f21-7d0e-729d-b67e-0db83a1cc855" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f8f21-7d0e-729d-b67e-0db83a1cc855" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_019f8f21-7d0e-7b5a-b205-6c11ad9822d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_019f8f21-7d0e-7b5a-b205-6c11ad9822d2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f8f21-7d0e-7845-b5e6-4e0ebdaca87f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f8f21-7d0e-7845-b5e6-4e0ebdaca87f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCashReceivedOnHedge_019f8f21-7d0e-724f-ad47-f88cf5852f97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCashReceivedOnHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DerivativeCashReceivedOnHedge_019f8f21-7d0e-724f-ad47-f88cf5852f97" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax_019f8f21-7d0e-7f02-8dfd-8b4c1c9b0854" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax_019f8f21-7d0e-7f02-8dfd-8b4c1c9b0854" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionOriginalDebtAmount1_019faae9-6978-7109-9ea6-5cf48ae20ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionOriginalDebtAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtConversionOriginalDebtAmount1_019faae9-6978-7109-9ea6-5cf48ae20ec2" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_019faae9-6978-724e-9eca-48e17cec294d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_019faae9-6978-724e-9eca-48e17cec294d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_019faae9-6978-799b-93e0-af91db2b78e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_019faae9-6978-799b-93e0-af91db2b78e9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtConversionConvertedInstrumentNonCashConversionExpense_019faaeb-e427-7df1-9ef6-36fd08fe95b2" xlink:href="stx-20260703.xsd#stx_DebtConversionConvertedInstrumentNonCashConversionExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtConversionConvertedInstrumentNonCashConversionExpense_019faaeb-e427-7df1-9ef6-36fd08fe95b2" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentRedemptionAmount_019faaf5-722b-7129-938d-b763a8c37ae5" xlink:href="stx-20260703.xsd#stx_DebtInstrumentRedemptionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentRedemptionAmount_019faaf5-722b-7129-938d-b763a8c37ae5" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentRedemptionGainLoss_019faaf7-8d5a-7947-ba10-6a5aea183325" xlink:href="stx-20260703.xsd#stx_DebtInstrumentRedemptionGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentRedemptionGainLoss_019faaf7-8d5a-7947-ba10-6a5aea183325" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/DebtNarrativeDetails_1" xlink:type="simple" xlink:href="stx-20260703.xsd#DebtNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/DebtNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" 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_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" 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_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f8f21-7d0e-70ba-adc3-81b8840c863d" 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_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f8f21-7d0e-70ba-adc3-81b8840c863d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-70ba-adc3-81b8840c863d_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_019f8f21-7d0e-70ba-adc3-81b8840c863d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-70ba-adc3-81b8840c863d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" 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_019f8f21-7d0e-70ba-adc3-81b8840c863d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f8f21-7d0e-75ea-8c84-dcafa352452d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_us-gaap_SeniorNotesMember_019f8f21-7d0e-75ea-8c84-dcafa352452d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-7878-82a6-a71dcf428d6f" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-7878-82a6-a71dcf428d6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-791f-aae2-41ca6544a114" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-791f-aae2-41ca6544a114" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7985-82ef-9624f8475394" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7985-82ef-9624f8475394" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_TermsLoansA1A2AndA3Member_019f8f21-7d0e-7ce9-8d01-59fc6dc39f15" xlink:href="stx-20260703.xsd#stx_TermsLoansA1A2AndA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_TermsLoansA1A2AndA3Member_019f8f21-7d0e-7ce9-8d01-59fc6dc39f15" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_019f8f21-7d0e-7f3a-90de-8357275eb6a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_us-gaap_ConvertibleDebtMember_019f8f21-7d0e-7f3a-90de-8357275eb6a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorUnsecuredRevolvingCreditFacilityMember_019f8f21-7d0e-7e36-a117-18fbd3564c69" xlink:href="stx-20260703.xsd#stx_SeniorUnsecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_SeniorUnsecuredRevolvingCreditFacilityMember_019f8f21-7d0e-7e36-a117-18fbd3564c69" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NewCreditAgreementMember_019f8f21-7d0e-795b-b9eb-90c3430ed75b" xlink:href="stx-20260703.xsd#stx_NewCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f8f21-7d0e-7aad-a027-9f07ef3b428c" xlink:to="loc_stx_NewCreditAgreementMember_019f8f21-7d0e-795b-b9eb-90c3430ed75b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7566-b91a-6b7b13beb872_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7566-b91a-6b7b13beb872_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-7566-b91a-6b7b13beb872" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-7721-96a6-7eceea175127" xlink:href="stx-20260703.xsd#stx_SeniorNotes4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-7721-96a6-7eceea175127" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-74ed-80b9-30672465b6c6" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-74ed-80b9-30672465b6c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-73cd-89b6-32078a5f6de2" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-73cd-89b6-32078a5f6de2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-785d-bad6-ce827b9fe656" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-785d-bad6-ce827b9fe656" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-754f-b5e9-a825ba1e58ea" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-754f-b5e9-a825ba1e58ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNote350PercentDueJune2028Member_019f8f21-7d0e-7361-9237-44325afac286" xlink:href="stx-20260703.xsd#stx_SeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNote350PercentDueJune2028Member_019f8f21-7d0e-7361-9237-44325afac286" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7d0e-74bc-a7ac-9997ca7df16b" xlink:href="stx-20260703.xsd#stx_ConvertibleSeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7d0e-74bc-a7ac-9997ca7df16b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f8f21-7d0e-7de6-abab-c3072733c237" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f8f21-7d0e-7de6-abab-c3072733c237" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019faaf1-64e9-74ae-8c42-b5405efb7969" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20292Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019faaf1-64e9-74ae-8c42-b5405efb7969" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019faaf1-64e9-7fd3-a1a6-ce6c86cac0ea" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019faaf1-64e9-7fd3-a1a6-ce6c86cac0ea" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20312Member_019faaf3-623c-77d8-a66a-60b5ba0e3f83" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7a01-a9b5-072163283ac8" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20312Member_019faaf3-623c-77d8-a66a-60b5ba0e3f83" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-71bf-9801-378cc4d14e62_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:to="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-71bf-9801-378cc4d14e62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f8f21-7d0e-71bf-9801-378cc4d14e62" xlink:to="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MediumTermNotesMember_019f8f21-7d0e-70c4-9933-a77246a1b5db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MediumTermNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:to="loc_us-gaap_MediumTermNotesMember_019f8f21-7d0e-70c4-9933-a77246a1b5db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019f8f21-7d0e-74e4-a673-7aa5c5b3dba5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:to="loc_us-gaap_LetterOfCreditMember_019f8f21-7d0e-74e4-a673-7aa5c5b3dba5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SwingLineLoansMember_019f8f21-7d0e-7ea2-9956-54154e86258e" xlink:href="stx-20260703.xsd#stx_SwingLineLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f8f21-7d0e-764f-9ee6-14e1a189bcab" xlink:to="loc_stx_SwingLineLoansMember_019f8f21-7d0e-7ea2-9956-54154e86258e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7d0e-76ab-8d78-1f89cb97616d" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_srt_RangeAxis_019f8f21-7d0e-76ab-8d78-1f89cb97616d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-76ab-8d78-1f89cb97616d_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_019f8f21-7d0e-76ab-8d78-1f89cb97616d" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-76ab-8d78-1f89cb97616d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7d0e-7522-aff9-3ad0d875189c" 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_019f8f21-7d0e-76ab-8d78-1f89cb97616d" xlink:to="loc_srt_RangeMember_019f8f21-7d0e-7522-aff9-3ad0d875189c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7d0e-7661-bc37-6f0cf881b62d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7d0e-7522-aff9-3ad0d875189c" xlink:to="loc_srt_MinimumMember_019f8f21-7d0e-7661-bc37-6f0cf881b62d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7d0e-7547-94c5-5c2022927b3c" 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_019f8f21-7d0e-7522-aff9-3ad0d875189c" xlink:to="loc_srt_MaximumMember_019f8f21-7d0e-7547-94c5-5c2022927b3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019f8f21-7d0e-7751-a077-c11b2d1976a9" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_srt_StatementScenarioAxis_019f8f21-7d0e-7751-a077-c11b2d1976a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-7751-a077-c11b2d1976a9_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_019f8f21-7d0e-7751-a077-c11b2d1976a9" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-7751-a077-c11b2d1976a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-788e-96fb-9b3c47df59ea" 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_019f8f21-7d0e-7751-a077-c11b2d1976a9" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019f8f21-7d0e-788e-96fb-9b3c47df59ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019f8f21-7d0e-7595-b4d3-25c7cf07c9fb" 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_019f8f21-7d0e-788e-96fb-9b3c47df59ea" xlink:to="loc_srt_ScenarioForecastMember_019f8f21-7d0e-7595-b4d3-25c7cf07c9fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f8f21-7d0e-7e4a-9034-c89515ad75d5" 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_DebtInstrumentTable_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f8f21-7d0e-7e4a-9034-c89515ad75d5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7e4a-9034-c89515ad75d5_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_019f8f21-7d0e-7e4a-9034-c89515ad75d5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7e4a-9034-c89515ad75d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7d3d-8d59-27197cc15a15" 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_019f8f21-7d0e-7e4a-9034-c89515ad75d5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7d3d-8d59-27197cc15a15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019f8f21-7d0e-75fa-96e5-40b7a67d461e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f8f21-7d0e-7d3d-8d59-27197cc15a15" xlink:to="loc_us-gaap_InterestRateSwapMember_019f8f21-7d0e-75fa-96e5-40b7a67d461e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019faaf5-d6dc-7c60-b609-70e8163acccd" 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_019f8f21-7d0e-7ae7-a51b-9458ecd38a51" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019faaf5-d6dc-7c60-b609-70e8163acccd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-7c60-b609-70e8163acccd_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_019faaf5-d6dc-7c60-b609-70e8163acccd" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-7c60-b609-70e8163acccd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-77e6-8120-06315413a5e4" 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_019faaf5-d6dc-7c60-b609-70e8163acccd" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019faaf5-d6dc-77e6-8120-06315413a5e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019faaf5-f1ca-7e6a-a796-73efe2a68c23" 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_019faaf5-d6dc-77e6-8120-06315413a5e4" xlink:to="loc_us-gaap_SubsequentEventMember_019faaf5-f1ca-7e6a-a796-73efe2a68c23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-76e3-a22e-45cb79f9bef1" 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_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-76e3-a22e-45cb79f9bef1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-7ea6-8ed3-1d23db9313e3" 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_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-7ea6-8ed3-1d23db9313e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f8f21-7d0e-746e-b35d-aebf42d11487" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f8f21-7d0e-746e-b35d-aebf42d11487" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnRepurchaseOfDebtInstrument_019f8f21-7d0e-7632-a0eb-7c5b550bc7e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnRepurchaseOfDebtInstrument"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_GainLossOnRepurchaseOfDebtInstrument_019f8f21-7d0e-7632-a0eb-7c5b550bc7e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentCovenantLeverageRatioMaximum_019f8f21-7d0e-77f7-b3e0-a2e25e1b4e25" xlink:href="stx-20260703.xsd#stx_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentCovenantLeverageRatioMaximum_019f8f21-7d0e-77f7-b3e0-a2e25e1b4e25" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentOverAllotmentOptionAmount_019f8f21-7d0e-7b38-889f-abdc5420d913" xlink:href="stx-20260703.xsd#stx_DebtInstrumentOverAllotmentOptionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentOverAllotmentOptionAmount_019f8f21-7d0e-7b38-889f-abdc5420d913" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_CappedCallTransactionPricePerShare_019f8f21-7d0e-77ad-bd95-c0f52ab8c4a8" xlink:href="stx-20260703.xsd#stx_CappedCallTransactionPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_CappedCallTransactionPricePerShare_019f8f21-7d0e-77ad-bd95-c0f52ab8c4a8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019f8f21-7d0e-74d6-9dfc-92c061640f45" 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_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_InterestExpenseDebt_019f8f21-7d0e-74d6-9dfc-92c061640f45" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f8f21-7d0e-729d-b67e-0db83a1cc855" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f8f21-7d0e-729d-b67e-0db83a1cc855" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_019f8f21-7d0e-7b5a-b205-6c11ad9822d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_019f8f21-7d0e-7b5a-b205-6c11ad9822d2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f8f21-7d0e-7845-b5e6-4e0ebdaca87f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f8f21-7d0e-7845-b5e6-4e0ebdaca87f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCashReceivedOnHedge_019f8f21-7d0e-724f-ad47-f88cf5852f97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCashReceivedOnHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DerivativeCashReceivedOnHedge_019f8f21-7d0e-724f-ad47-f88cf5852f97" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax_019f8f21-7d0e-7f02-8dfd-8b4c1c9b0854" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax_019f8f21-7d0e-7f02-8dfd-8b4c1c9b0854" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionOriginalDebtAmount1_019faae9-6978-7109-9ea6-5cf48ae20ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionOriginalDebtAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtConversionOriginalDebtAmount1_019faae9-6978-7109-9ea6-5cf48ae20ec2" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_019faae9-6978-724e-9eca-48e17cec294d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_019faae9-6978-724e-9eca-48e17cec294d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_019faae9-6978-799b-93e0-af91db2b78e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_019faae9-6978-799b-93e0-af91db2b78e9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtConversionConvertedInstrumentNonCashConversionExpense_019faaeb-e427-7df1-9ef6-36fd08fe95b2" xlink:href="stx-20260703.xsd#stx_DebtConversionConvertedInstrumentNonCashConversionExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtConversionConvertedInstrumentNonCashConversionExpense_019faaeb-e427-7df1-9ef6-36fd08fe95b2" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentRedemptionAmount_019faaf5-722b-7129-938d-b763a8c37ae5" xlink:href="stx-20260703.xsd#stx_DebtInstrumentRedemptionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentRedemptionAmount_019faaf5-722b-7129-938d-b763a8c37ae5" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DebtInstrumentRedemptionGainLoss_019faaf7-8d5a-7947-ba10-6a5aea183325" xlink:href="stx-20260703.xsd#stx_DebtInstrumentRedemptionGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-7dd9-b977-dfed8a04a54e" xlink:to="loc_stx_DebtInstrumentRedemptionGainLoss_019faaf7-8d5a-7947-ba10-6a5aea183325" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/DebtTenderedDebtAgreementDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#DebtTenderedDebtAgreementDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/DebtTenderedDebtAgreementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7d0e-72c7-8268-dfc820f5a13d" 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_019f8f21-7d0e-7940-a15e-92210e32b8a7" 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_019f8f21-7d0e-72c7-8268-dfc820f5a13d" xlink:to="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7940-a15e-92210e32b8a7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-794b-a72e-59798673e221" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f8f21-7d0e-7940-a15e-92210e32b8a7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-794b-a72e-59798673e221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-794b-a72e-59798673e221_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-794b-a72e-59798673e221" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-794b-a72e-59798673e221_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7d0e-794b-a72e-59798673e221" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-7359-b0a9-9b88dc370085" xlink:href="stx-20260703.xsd#stx_SeniorNotes4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7d0e-7359-b0a9-9b88dc370085" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20291Member_019f8f21-7d0e-7d13-a61c-409d60ea1817" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20291Member_019f8f21-7d0e-7d13-a61c-409d60ea1817" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-72cd-b925-204f89bef1ad" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7d0e-72cd-b925-204f89bef1ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-700e-81c4-e6d35ff5124e" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7d0e-700e-81c4-e6d35ff5124e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-7f78-92a0-84118acc67d2" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7d0e-7f78-92a0-84118acc67d2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-78cd-a9e3-8e7e2a87201b" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7d0e-78cd-a9e3-8e7e2a87201b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7d17-8c40-323ee6c6e843" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7d0e-7d17-8c40-323ee6c6e843" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Seniornote5.75percentdueDecember2034Member_019f8f21-7d0e-774c-89d4-1b06251edbf9" xlink:href="stx-20260703.xsd#stx_Seniornote5.75percentdueDecember2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7d0e-7f60-95b0-acf13c1e0ce8" xlink:to="loc_stx_Seniornote5.75percentdueDecember2034Member_019f8f21-7d0e-774c-89d4-1b06251edbf9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-720b-80ad-5eda14185d50" 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_019f8f21-7d0e-72c7-8268-dfc820f5a13d" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7d0e-720b-80ad-5eda14185d50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-74db-973f-eca10cb62194" 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_019f8f21-7d0e-72c7-8268-dfc820f5a13d" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019f8f21-7d0e-74db-973f-eca10cb62194" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019f8f21-7d0e-78e8-8a2f-ebff83020617" 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_DebtInstrumentLineItems_019f8f21-7d0e-72c7-8268-dfc820f5a13d" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019f8f21-7d0e-78e8-8a2f-ebff83020617" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable_019f8f21-7dbb-7304-8a20-37e33675df82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable_019f8f21-7dbb-7304-8a20-37e33675df82" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019f8f21-7dbb-71d1-a6a1-6753664e5d76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable_019f8f21-7dbb-7304-8a20-37e33675df82" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019f8f21-7dbb-71d1-a6a1-6753664e5d76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-71d1-a6a1-6753664e5d76_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019f8f21-7dbb-71d1-a6a1-6753664e5d76" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-71d1-a6a1-6753664e5d76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-7084-9009-474c066743cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019f8f21-7dbb-71d1-a6a1-6753664e5d76" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-7084-9009-474c066743cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember_019f8f21-7dbb-7d80-a2ab-77b8e5dd80cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InternalRevenueServiceIRSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-7084-9009-474c066743cc" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember_019f8f21-7dbb-7d80-a2ab-77b8e5dd80cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_019f8f21-7dbb-7588-9777-20874cac5610" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-7084-9009-474c066743cc" xlink:to="loc_us-gaap_ForeignCountryMember_019f8f21-7dbb-7588-9777-20874cac5610" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019fb361-f18a-7f4f-92ec-445f4d25dca1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019f8f21-7dbb-7084-9009-474c066743cc" xlink:to="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019fb361-f18a-7f4f-92ec-445f4d25dca1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7dbb-7f39-9671-238575526a53" 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_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable_019f8f21-7dbb-7304-8a20-37e33675df82" xlink:to="loc_srt_RangeAxis_019f8f21-7dbb-7f39-9671-238575526a53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7dbb-7f39-9671-238575526a53_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_019f8f21-7dbb-7f39-9671-238575526a53" xlink:to="loc_srt_RangeMember_019f8f21-7dbb-7f39-9671-238575526a53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7dbb-7904-8234-c5f03b62ede6" 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_019f8f21-7dbb-7f39-9671-238575526a53" xlink:to="loc_srt_RangeMember_019f8f21-7dbb-7904-8234-c5f03b62ede6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7dbb-7820-896c-bdb849e2f7dd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7dbb-7904-8234-c5f03b62ede6" xlink:to="loc_srt_MinimumMember_019f8f21-7dbb-7820-896c-bdb849e2f7dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7dbb-790d-9e82-caa405890224" 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_019f8f21-7dbb-7904-8234-c5f03b62ede6" xlink:to="loc_srt_MaximumMember_019f8f21-7dbb-790d-9e82-caa405890224" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_019f8f21-7dbb-7061-8b62-fb2294acedae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_019f8f21-7dbb-7061-8b62-fb2294acedae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_019f8f21-7dbb-78cd-83d1-71942038a6e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_019f8f21-7dbb-78cd-83d1-71942038a6e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_019f8f21-7dbb-7826-a0e5-8022a2b357f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_OperatingLossCarryforwards_019f8f21-7dbb-7826-a0e5-8022a2b357f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_019f8f21-7dbb-7213-9d15-a4d60748250a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxCreditCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_019f8f21-7dbb-7213-9d15-a4d60748250a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_TaxCreditCarryforwardAmountNotSubjectToExpiration_019f9034-13be-7405-ba23-7b2b96c9e43e" xlink:href="stx-20260703.xsd#stx_TaxCreditCarryforwardAmountNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_stx_TaxCreditCarryforwardAmountNotSubjectToExpiration_019f9034-13be-7405-ba23-7b2b96c9e43e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NetOperatingLossesSubjectToAnnualLimitationOnUse_019f8f21-7dbb-7b04-94a1-d7e747c270b6" xlink:href="stx-20260703.xsd#stx_NetOperatingLossesSubjectToAnnualLimitationOnUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_stx_NetOperatingLossesSubjectToAnnualLimitationOnUse_019f8f21-7dbb-7b04-94a1-d7e747c270b6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_CapitalLossCarryforwardAmount_019f8f21-7dbb-70f3-b6d3-7aa430934b3e" xlink:href="stx-20260703.xsd#stx_CapitalLossCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_stx_CapitalLossCarryforwardAmount_019f8f21-7dbb-70f3-b6d3-7aa430934b3e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_TaxCreditCarryforwardsSubjectToAnnualLimitationOnUse_019f8f21-7dbb-7815-a83d-b4ab4bdf5c72" xlink:href="stx-20260703.xsd#stx_TaxCreditCarryforwardsSubjectToAnnualLimitationOnUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_stx_TaxCreditCarryforwardsSubjectToAnnualLimitationOnUse_019f8f21-7dbb-7815-a83d-b4ab4bdf5c72" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_019f8f21-7dbb-7dd1-a42e-71d42bc9f3fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_019f8f21-7dbb-7dd1-a42e-71d42bc9f3fe" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxHolidayAggregateDollarAmount_019f8f21-7dbb-7935-a5a3-3247d4df7f7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxHolidayAggregateDollarAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_IncomeTaxHolidayAggregateDollarAmount_019f8f21-7dbb-7935-a5a3-3247d4df7f7d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare_019f8f21-7dbb-793e-bfcd-6d3f9539a5cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare_019f8f21-7dbb-793e-bfcd-6d3f9539a5cd" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_019f8f21-7dbb-7a3b-8f5c-013a3194a327" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_019f8f21-7dbb-745a-b12a-c201298546fa" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_019f8f21-7dbb-7a3b-8f5c-013a3194a327" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/IncomeTaxesScheduleofReconciliationBetweenIncomeatStatutoryRateandEffectiveRateDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#IncomeTaxesScheduleofReconciliationBetweenIncomeatStatutoryRateandEffectiveRateDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/IncomeTaxesScheduleofReconciliationBetweenIncomeatStatutoryRateandEffectiveRateDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019f8fe4-7cbd-7a42-b304-31dbccd42b14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019f8fe4-7cbd-71e2-b993-2b17cb5db62c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019f8fe4-7cbd-7a42-b304-31dbccd42b14" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019f8fe4-7cbd-71e2-b993-2b17cb5db62c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019f8fe5-15c9-73e7-ba27-675d0ab73ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019f8fe4-7cbd-71e2-b993-2b17cb5db62c" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019f8fe5-15c9-73e7-ba27-675d0ab73ca6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019f8fe5-15c9-73e7-ba27-675d0ab73ca6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019f8fe5-15c9-73e7-ba27-675d0ab73ca6" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019f8fe5-15c9-73e7-ba27-675d0ab73ca6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019f8fe5-15c9-7a48-a2bd-873368784239" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019f8fe5-15c9-73e7-ba27-675d0ab73ca6" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019f8fe5-15c9-7a48-a2bd-873368784239" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_019f8ff5-db0f-79e2-8b66-0b8be915f3f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019f8fe5-15c9-7a48-a2bd-873368784239" xlink:to="loc_us-gaap_DomesticCountryMember_019f8ff5-db0f-79e2-8b66-0b8be915f3f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SG_019f8fe5-15ca-7e9b-9ef7-2ef05fc7241c" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_SG"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019f8ff5-db0f-79e2-8b66-0b8be915f3f9" xlink:to="loc_country_SG_019f8fe5-15ca-7e9b-9ef7-2ef05fc7241c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_019f8ff6-083e-71c1-9d9d-01faac6aa8a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019f8fe5-15c9-7a48-a2bd-873368784239" xlink:to="loc_us-gaap_ForeignCountryMember_019f8ff6-083e-71c1-9d9d-01faac6aa8a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019f8ff5-2feb-70f5-a86d-108ec3674b52" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019f8ff6-083e-71c1-9d9d-01faac6aa8a5" xlink:to="loc_country_US_019f8ff5-2feb-70f5-a86d-108ec3674b52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019f8ff5-2feb-7e62-b05f-2ca874ecbbd4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019f8ff6-083e-71c1-9d9d-01faac6aa8a5" xlink:to="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019f8ff5-2feb-7e62-b05f-2ca874ecbbd4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019f8fe4-7cbd-7a42-b304-31dbccd42b14" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_019f8f21-7dbb-7a21-a179-f1fa270bb163" 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_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_019f8f21-7dbb-7a21-a179-f1fa270bb163" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_019f8f21-7dbb-7eed-9cd5-db382cce5901" 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_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_019f8f21-7dbb-7eed-9cd5-db382cce5901" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseInterestExpenseAmount_019f8fe3-a829-7986-ac19-c5584e3ef5ab" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseInterestExpenseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseInterestExpenseAmount_019f8fe3-a829-7986-ac19-c5584e3ef5ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther_019f8fd8-a1d2-7b72-a021-fd7d40b33cfa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther_019f8fd8-a1d2-7b72-a021-fd7d40b33cfa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_019f8f21-7dbb-7484-a88a-38f783a25829" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_019f8f21-7dbb-7484-a88a-38f783a25829" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsInternalReOrganizationAmount_019f8ff2-2af5-7738-8e0b-e418b3758e12" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsInternalReOrganizationAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsInternalReOrganizationAmount_019f8ff2-2af5-7738-8e0b-e418b3758e12" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_019f8f21-7dbb-740e-8af2-bcc7fbe7adaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsResearch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_019f8f21-7dbb-740e-8af2-bcc7fbe7adaa" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxContingencies_019f8fd8-d0bd-730a-b339-0e154c7b7106" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationTaxContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxContingencies_019f8fd8-d0bd-730a-b339-0e154c7b7106" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_019f8fd7-0453-7bf1-9c1b-ca717b2f868a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_019f8fd7-0453-7bf1-9c1b-ca717b2f868a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationCapitalLossCarryforward_019f8f21-7dbb-703a-94da-d6a2f8b98a86" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationCapitalLossCarryforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationCapitalLossCarryforward_019f8f21-7dbb-703a-94da-d6a2f8b98a86" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_019f8f21-7dbb-7a57-a999-a2f54013656d" 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_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_019f8f21-7dbb-7a57-a999-a2f54013656d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferentialAndOtherForeignTaxRateImpactsAmount_019fcd03-ffd4-7aaa-9d2c-2cecd9fd7663" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferentialAndOtherForeignTaxRateImpactsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferentialAndOtherForeignTaxRateImpactsAmount_019fcd03-ffd4-7aaa-9d2c-2cecd9fd7663" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsQualifiedDomesticMinimumTopUpTaxAmount_019f8ff3-0782-76cd-8f98-26e66f7c6702" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsQualifiedDomesticMinimumTopUpTaxAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsQualifiedDomesticMinimumTopUpTaxAmount_019f8ff3-0782-76cd-8f98-26e66f7c6702" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019f8f21-7dbb-7ced-807e-3daab2eb0e2a" 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_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019f8fe7-6b51-7523-9d84-bf9decdf4591" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019f8f21-7dbb-7ced-807e-3daab2eb0e2a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019f8fe4-7cbd-7a42-b304-31dbccd42b14" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_019f8f21-7dbb-71e0-9dab-e0ba7e6ac9fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_019f8f21-7dbb-71e0-9dab-e0ba7e6ac9fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_019f8fd6-d331-7696-9081-0f6983b477e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_019f8fd6-d331-7696-9081-0f6983b477e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_019f8fd7-0453-7454-bd67-9f7efbb4d1bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_019f8fd7-0453-7454-bd67-9f7efbb4d1bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_019f8fd7-4a1c-7691-b532-817557986f36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_019f8fd7-4a1c-7691-b532-817557986f36" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferentialAndOtherForeignTaxRateImpactsPercent_019fcd04-54b5-7f74-92bf-9a03a597bcef" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferentialAndOtherForeignTaxRateImpactsPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferentialAndOtherForeignTaxRateImpactsPercent_019fcd04-54b5-7f74-92bf-9a03a597bcef" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_019f8fd8-0f31-7a09-87a2-e72b2354fdf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_019f8fd8-0f31-7a09-87a2-e72b2354fdf2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseInterestExpensePercent_019f8fe3-fbc1-7115-82bb-acb8000449b0" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseInterestExpensePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseInterestExpensePercent_019f8fe3-fbc1-7115-82bb-acb8000449b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther_019f8fd8-b359-73b3-858f-89e1c87d35d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther_019f8fd8-b359-73b3-858f-89e1c87d35d5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_019f8fd8-e19e-7d44-8cae-a78889d0bd90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_019f8fd8-e19e-7d44-8cae-a78889d0bd90" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsInternalReOrganizationPercent_019f8ff2-831f-7327-a226-c9fbdc9604b5" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsInternalReOrganizationPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsInternalReOrganizationPercent_019f8ff2-831f-7327-a226-c9fbdc9604b5" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsQualifiedDomesticMinimumTopUpTaxPercent_019f8ff3-15d3-7d9d-956c-95a53db4f08a" xlink:href="stx-20260703.xsd#stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsQualifiedDomesticMinimumTopUpTaxPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_stx_EffectiveIncomeTaxRateReconciliationOtherAdjustmentsQualifiedDomesticMinimumTopUpTaxPercent_019f8ff3-15d3-7d9d-956c-95a53db4f08a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019f8fd9-c68e-7479-b4b6-f6bf77dc1a41" 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_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019f8fe7-10ee-7feb-936b-3ed4bbbbb924" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019f8fd9-c68e-7479-b4b6-f6bf77dc1a41" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/FairValueNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#FairValueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/FairValueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" 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_019f8f21-7dbb-7e81-89a1-2824580046ea" 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_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7dbb-78d5-9bd6-16aa0f28ce0e" 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f8f21-7dbb-78d5-9bd6-16aa0f28ce0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f8f21-7dbb-7db2-a696-3e7c64e5da83" 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_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f8f21-7dbb-7db2-a696-3e7c64e5da83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-7db2-a696-3e7c64e5da83_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_019f8f21-7dbb-7db2-a696-3e7c64e5da83" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-7db2-a696-3e7c64e5da83_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-78ea-98c5-dc18cb8bf0b3" 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_019f8f21-7dbb-7db2-a696-3e7c64e5da83" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-78ea-98c5-dc18cb8bf0b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f8f21-7dbb-7896-b734-1fa71d286866" 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_019f8f21-7dbb-78ea-98c5-dc18cb8bf0b3" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f8f21-7dbb-7896-b734-1fa71d286866" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7851-a795-4ef17e5e10af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7851-a795-4ef17e5e10af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7d15-af80-c42212cb35eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7d15-af80-c42212cb35eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019f8f21-7dbb-7182-bd24-7ea6fb4968fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7d15-af80-c42212cb35eb" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019f8f21-7dbb-7182-bd24-7ea6fb4968fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019f8f21-7dbb-73ea-bb0c-76d162bb2942" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019f8f21-7dbb-73ea-bb0c-76d162bb2942" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019f8f21-7dbb-799d-8b99-59ee48ed341b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019f8f21-7dbb-799d-8b99-59ee48ed341b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NetGainsLossesFromInvestmentUnderMeasurementAlternative_019f8f21-7dbb-7e4d-bc9d-d7693270eb10" xlink:href="stx-20260703.xsd#stx_NetGainsLossesFromInvestmentUnderMeasurementAlternative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_stx_NetGainsLossesFromInvestmentUnderMeasurementAlternative_019f8f21-7dbb-7e4d-bc9d-d7693270eb10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019f8f21-7dbb-729b-a240-8c8d118d0fa2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019f8f21-7dbb-729b-a240-8c8d118d0fa2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_019f8f21-7dbb-79aa-ba03-913b6fbf9879" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_019f8f21-7dbb-79aa-ba03-913b6fbf9879" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019f8f21-7dbb-7d6c-b18b-d08022dc0e29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019f8f21-7dbb-7d6c-b18b-d08022dc0e29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseImpairmentLoss_019f8f21-7dbb-77bc-b0df-0880e59ca48c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_OperatingLeaseImpairmentLoss_019f8f21-7dbb-77bc-b0df-0880e59ca48c" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/FairValueNarrativeDetails_1" xlink:type="simple" xlink:href="stx-20260703.xsd#FairValueNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/FairValueNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" 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_019f8f21-7dbb-7e81-89a1-2824580046ea" 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_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f8f21-7dbb-7db2-a696-3e7c64e5da83" 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_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f8f21-7dbb-7db2-a696-3e7c64e5da83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-7db2-a696-3e7c64e5da83_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_019f8f21-7dbb-7db2-a696-3e7c64e5da83" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-7db2-a696-3e7c64e5da83_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-78ea-98c5-dc18cb8bf0b3" 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_019f8f21-7dbb-7db2-a696-3e7c64e5da83" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-78ea-98c5-dc18cb8bf0b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f8f21-7dbb-7896-b734-1fa71d286866" 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_019f8f21-7dbb-78ea-98c5-dc18cb8bf0b3" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f8f21-7dbb-7896-b734-1fa71d286866" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7e81-89a1-2824580046ea" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7851-a795-4ef17e5e10af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7851-a795-4ef17e5e10af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7d15-af80-c42212cb35eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7851-a795-4ef17e5e10af" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7d15-af80-c42212cb35eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019f8f21-7dbb-7182-bd24-7ea6fb4968fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7d15-af80-c42212cb35eb" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019f8f21-7dbb-7182-bd24-7ea6fb4968fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019f8f21-7dbb-73ea-bb0c-76d162bb2942" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019f8f21-7dbb-73ea-bb0c-76d162bb2942" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019f8f21-7dbb-799d-8b99-59ee48ed341b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019f8f21-7dbb-799d-8b99-59ee48ed341b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NetGainsLossesFromInvestmentUnderMeasurementAlternative_019f8f21-7dbb-7e4d-bc9d-d7693270eb10" xlink:href="stx-20260703.xsd#stx_NetGainsLossesFromInvestmentUnderMeasurementAlternative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_stx_NetGainsLossesFromInvestmentUnderMeasurementAlternative_019f8f21-7dbb-7e4d-bc9d-d7693270eb10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019f8f21-7dbb-729b-a240-8c8d118d0fa2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019f8f21-7dbb-729b-a240-8c8d118d0fa2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_019f8f21-7dbb-79aa-ba03-913b6fbf9879" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_019f8f21-7dbb-79aa-ba03-913b6fbf9879" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019f8f21-7dbb-7d6c-b18b-d08022dc0e29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019f8f21-7dbb-7d6c-b18b-d08022dc0e29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseImpairmentLoss_019f8f21-7dbb-77bc-b0df-0880e59ca48c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-74ae-bbfd-f408dcc18c88" xlink:to="loc_us-gaap_OperatingLeaseImpairmentLoss_019f8f21-7dbb-77bc-b0df-0880e59ca48c" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/FairValueScheduleofFairValuebyBalanceSheetGroupingMeasuredonRecurringBasisDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#FairValueScheduleofFairValuebyBalanceSheetGroupingMeasuredonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/FairValueScheduleofFairValuebyBalanceSheetGroupingMeasuredonRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-79ce-9b22-365eb9b51cb9" 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_019f8f21-7dbb-7b7a-9686-4ad0b52b7fbc" 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_019f8f21-7dbb-79ce-9b22-365eb9b51cb9" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7b7a-9686-4ad0b52b7fbc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7aff-a7fd-8c1b3ced904e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7b7a-9686-4ad0b52b7fbc" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7aff-a7fd-8c1b3ced904e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7aff-a7fd-8c1b3ced904e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7aff-a7fd-8c1b3ced904e" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-7aff-a7fd-8c1b3ced904e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-75df-8fa1-82b7dde7e20c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019f8f21-7dbb-7aff-a7fd-8c1b3ced904e" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-75df-8fa1-82b7dde7e20c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019f8f21-7dbb-73f1-a398-66dbdc9a2bd9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019f8f21-7dbb-75df-8fa1-82b7dde7e20c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019f8f21-7dbb-73f1-a398-66dbdc9a2bd9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f8f21-7dbb-77e3-b944-bf01547489c9" 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_019f8f21-7dbb-7b7a-9686-4ad0b52b7fbc" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f8f21-7dbb-77e3-b944-bf01547489c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-77e3-b944-bf01547489c9_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_019f8f21-7dbb-77e3-b944-bf01547489c9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-77e3-b944-bf01547489c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-7d9b-856e-261bb8b7b65b" 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_019f8f21-7dbb-77e3-b944-bf01547489c9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f8f21-7dbb-7d9b-856e-261bb8b7b65b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019f8f21-7dbb-74f5-a882-97aa80225f21" 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_019f8f21-7dbb-7d9b-856e-261bb8b7b65b" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019f8f21-7dbb-74f5-a882-97aa80225f21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019f8f21-7dbb-7063-9a73-9cfab3ed2a3c" 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_019f8f21-7dbb-7d9b-856e-261bb8b7b65b" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019f8f21-7dbb-7063-9a73-9cfab3ed2a3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f8f21-7dbb-7fd3-bc40-4fb4a948a056" 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_019f8f21-7dbb-7d9b-856e-261bb8b7b65b" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f8f21-7dbb-7fd3-bc40-4fb4a948a056" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_019f8f21-7dbb-73c8-9cfc-d7c3414da031" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f8f21-7dbb-7b7a-9686-4ad0b52b7fbc" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_019f8f21-7dbb-73c8-9cfc-d7c3414da031" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f8f21-7dbb-73c8-9cfc-d7c3414da031_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019f8f21-7dbb-73c8-9cfc-d7c3414da031" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f8f21-7dbb-73c8-9cfc-d7c3414da031_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f8f21-7dbb-7e54-83e5-a9dfc145d985" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019f8f21-7dbb-73c8-9cfc-d7c3414da031" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f8f21-7dbb-7e54-83e5-a9dfc145d985" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_019f8f21-7dbb-7ebc-a7fc-dad20bdd8322" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f8f21-7dbb-7e54-83e5-a9dfc145d985" xlink:to="loc_us-gaap_MoneyMarketFundsMember_019f8f21-7dbb-7ebc-a7fc-dad20bdd8322" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_TimedepositsandcertificatesofdepositMember_019f8f21-7dbb-775b-bc34-4e8e3db21c78" xlink:href="stx-20260703.xsd#stx_TimedepositsandcertificatesofdepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019f8f21-7dbb-7e54-83e5-a9dfc145d985" xlink:to="loc_stx_TimedepositsandcertificatesofdepositMember_019f8f21-7dbb-775b-bc34-4e8e3db21c78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019f8f21-7dbb-7a8b-b40f-49e8eb167264" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f8f21-7dbb-79ce-9b22-365eb9b51cb9" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019f8f21-7dbb-7a8b-b40f-49e8eb167264" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_CashandCashEquivalentsandShorttermInvestmentsFairValueDisclosure_019f8f21-7dbb-7756-93ee-4b1ed9033757" xlink:href="stx-20260703.xsd#stx_CashandCashEquivalentsandShorttermInvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019f8f21-7dbb-7a8b-b40f-49e8eb167264" xlink:to="loc_stx_CashandCashEquivalentsandShorttermInvestmentsFairValueDisclosure_019f8f21-7dbb-7756-93ee-4b1ed9033757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7dbb-76ae-8ecd-2e8c78b2f41b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019f8f21-7dbb-7a8b-b40f-49e8eb167264" xlink:to="loc_us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration_019f8f21-7dbb-76ae-8ecd-2e8c78b2f41b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019f8f21-7dbb-728c-a7f5-d85324c343fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019f8f21-7dbb-7a8b-b40f-49e8eb167264" xlink:to="loc_us-gaap_DerivativeAssets_019f8f21-7dbb-728c-a7f5-d85324c343fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019f8f21-7dbb-7beb-9f41-3f4cad9a8de3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019f8f21-7dbb-7a8b-b40f-49e8eb167264" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019f8f21-7dbb-7beb-9f41-3f4cad9a8de3" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/FairValueScheduleofCarryingValuesandEstimatedFairValuesofDebtInstrumentsDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#FairValueScheduleofCarryingValuesandEstimatedFairValuesofDebtInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/FairValueScheduleofCarryingValuesandEstimatedFairValuesofDebtInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" 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_FairValueByBalanceSheetGroupingTable_019f8f21-7dbb-7ce3-abb4-17dbac599ae3" 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_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019f8f21-7dbb-7ce3-abb4-17dbac599ae3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019f8f21-7dbb-76dc-92f8-3b62d1dd45ae" 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_019f8f21-7dbb-7ce3-abb4-17dbac599ae3" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019f8f21-7dbb-76dc-92f8-3b62d1dd45ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7dbb-76dc-92f8-3b62d1dd45ae_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_019f8f21-7dbb-76dc-92f8-3b62d1dd45ae" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7dbb-76dc-92f8-3b62d1dd45ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019f8f21-7dbb-78a0-9e74-f862e40ddc0a" 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_019f8f21-7dbb-76dc-92f8-3b62d1dd45ae" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019f8f21-7dbb-78a0-9e74-f862e40ddc0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7dbb-7ae6-91e3-439fe14f1444" 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_019f8f21-7dbb-78a0-9e74-f862e40ddc0a" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019f8f21-7dbb-7ae6-91e3-439fe14f1444" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019f8f21-7dbb-70cc-ad2d-5deecac834c9" 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_PortionAtFairValueFairValueDisclosureMember_019f8f21-7dbb-7ae6-91e3-439fe14f1444" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019f8f21-7dbb-70cc-ad2d-5deecac834c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019f8f21-7dbb-7564-91e2-1d0b1ba1a898" 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_PortionAtFairValueFairValueDisclosureMember_019f8f21-7dbb-7ae6-91e3-439fe14f1444" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019f8f21-7dbb-7564-91e2-1d0b1ba1a898" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7dbb-7e42-9934-7ce616c10084" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019f8f21-7dbb-7ce3-abb4-17dbac599ae3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7dbb-7e42-9934-7ce616c10084" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-7e42-9934-7ce616c10084_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7dbb-7e42-9934-7ce616c10084" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-7e42-9934-7ce616c10084_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f8f21-7dbb-7e42-9934-7ce616c10084" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7dbb-7a68-a847-020737804e77" xlink:href="stx-20260703.xsd#stx_SeniorNotes4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes4091PercentDueJune2029Member_019f8f21-7dbb-7a68-a847-020737804e77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20291Member_019f8f21-7dbb-776c-8394-23e68d7d56e7" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20291Member_019f8f21-7dbb-776c-8394-23e68d7d56e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7dbb-7c90-896f-20027322a736" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20291Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20291Member_019f8f21-7dbb-7c90-896f-20027322a736" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7dbb-7216-8d22-052f32b58888" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20311Member_019f8f21-7dbb-7216-8d22-052f32b58888" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7dbb-74af-9483-9e768163a942" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20311Member_019f8f21-7dbb-74af-9483-9e768163a942" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7dbb-7bc3-a5ce-e51ba865f885" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20311Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20311Member_019f8f21-7dbb-7bc3-a5ce-e51ba865f885" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7dbb-77cd-a815-d5b4e186e057" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20321Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20321Member_019f8f21-7dbb-77cd-a815-d5b4e186e057" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Seniornote5.75percentdueDecember2034Member_019f8f21-7dbb-7b94-8328-f4aef6332a78" xlink:href="stx-20260703.xsd#stx_Seniornote5.75percentdueDecember2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_Seniornote5.75percentdueDecember2034Member_019f8f21-7dbb-7b94-8328-f4aef6332a78" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7dbb-7c70-825d-3bfb66905c48" xlink:href="stx-20260703.xsd#stx_ConvertibleSeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_ConvertibleSeniorNote350PercentDueJune2028Member_019f8f21-7dbb-7c70-825d-3bfb66905c48" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNote4091PercentDueJune2029Member_019f8f21-7dbb-7fdd-b497-d0a0293feff1" xlink:href="stx-20260703.xsd#stx_SeniorNote4091PercentDueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNote4091PercentDueJune2029Member_019f8f21-7dbb-7fdd-b497-d0a0293feff1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes5.875PercentDueJuly2030Member_019f8f21-7dbb-7e5b-a77b-4731077a2202" xlink:href="stx-20260703.xsd#stx_SeniorNotes5.875PercentDueJuly2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes5.875PercentDueJuly2030Member_019f8f21-7dbb-7e5b-a77b-4731077a2202" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNote350PercentDueJune2028Member_019f9040-676f-7f74-810d-ad6fdf3a9f27" xlink:href="stx-20260703.xsd#stx_SeniorNote350PercentDueJune2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNote350PercentDueJune2028Member_019f9040-676f-7f74-810d-ad6fdf3a9f27" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes5750PercentDueDecember2034Member_019f9045-1a9d-76ec-9ae0-0744674a53e8" xlink:href="stx-20260703.xsd#stx_SeniorNotes5750PercentDueDecember2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes5750PercentDueDecember2034Member_019f9045-1a9d-76ec-9ae0-0744674a53e8" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes9.625PercentDueDecember20322Member_019f9048-c724-7fbd-acef-97a6316de8b4" xlink:href="stx-20260703.xsd#stx_SeniorNotes9.625PercentDueDecember20322Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes9.625PercentDueDecember20322Member_019f9048-c724-7fbd-acef-97a6316de8b4" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019f9049-1d8d-7bcd-b17e-1e9bfe3c9764" xlink:href="stx-20260703.xsd#stx_SeniorNotes4.125PercentDueJanuary20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes4.125PercentDueJanuary20312Member_019f9049-1d8d-7bcd-b17e-1e9bfe3c9764" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.50PercentDueJuly20312Member_019f9052-e0cd-7671-94b4-58bc0d86db4b" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.50PercentDueJuly20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes8.50PercentDueJuly20312Member_019f9052-e0cd-7671-94b4-58bc0d86db4b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019f9053-6c55-7bf3-b268-ddbdc374acf4" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.125PercentDueJuly20292Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes3.125PercentDueJuly20292Member_019f9053-6c55-7bf3-b268-ddbdc374acf4" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes3.375PercentDueJuly20312Member_019f9053-fbd9-7b96-8caf-8700a006b7ef" xlink:href="stx-20260703.xsd#stx_SeniorNotes3.375PercentDueJuly20312Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes3.375PercentDueJuly20312Member_019f9053-fbd9-7b96-8caf-8700a006b7ef" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeniorNotes8.25PercentDueDecember20292Member_019f9057-4d90-7a15-bd43-2c0ccbcda1bc" xlink:href="stx-20260703.xsd#stx_SeniorNotes8.25PercentDueDecember20292Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f8f21-7dbb-785e-8c34-34b875221c10" xlink:to="loc_stx_SeniorNotes8.25PercentDueDecember20292Member_019f9057-4d90-7a15-bd43-2c0ccbcda1bc" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotes_019f8f21-7dbb-7536-8e09-b92efea7b3dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_SeniorNotes_019f8f21-7dbb-7536-8e09-b92efea7b3dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019f8f21-7dbb-7110-bee3-56dd75f068ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019f8f21-7dbb-7110-bee3-56dd75f068ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f8f21-7dbb-799c-8b70-4edc89be7242" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_LongTermDebt_019f8f21-7dbb-799c-8b70-4edc89be7242" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019f8f21-7dbb-79c1-b323-6282723a0741" 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_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_LongTermDebtCurrent_019f8f21-7dbb-79c1-b323-6282723a0741" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019f8f21-7dbb-7ce8-a98c-9d0835f4947c" 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_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019f8f21-7dbb-7ce8-a98c-9d0835f4947c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7dbb-7f4d-9076-8d886ec367f3" 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_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f8f21-7dbb-7f4d-9076-8d886ec367f3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019f8f21-7dbb-770a-8581-2ce1781818ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f8f21-7dbb-76b6-90d9-0c4d50e17118" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019f8f21-7dbb-770a-8581-2ce1781818ad" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/SharebasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#SharebasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/SharebasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-7333-87eb-8f497ce330fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-7333-87eb-8f497ce330fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7a72-9105-9e2a6093a0e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-7333-87eb-8f497ce330fa" xlink:to="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7a72-9105-9e2a6093a0e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7a72-9105-9e2a6093a0e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7a72-9105-9e2a6093a0e4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7a72-9105-9e2a6093a0e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7a72-9105-9e2a6093a0e4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019f8f21-7dbb-738e-a676-4bac8cd096ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:to="loc_us-gaap_StockCompensationPlanMember_019f8f21-7dbb-738e-a676-4bac8cd096ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_019f8f21-7dbb-729b-9458-4437fd0e3849" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:to="loc_us-gaap_EmployeeStockMember_019f8f21-7dbb-729b-9458-4437fd0e3849" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019f8f21-7dbb-7931-8f95-0d495b841a61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019f8f21-7dbb-7931-8f95-0d495b841a61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f8f21-7dbb-79d8-ae20-eeec2e1df338" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f8f21-7dbb-79d8-ae20-eeec2e1df338" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019f8f21-7dbb-70c4-ad12-275c16e4a01b" 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_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:to="loc_us-gaap_PerformanceSharesMember_019f8f21-7dbb-70c4-ad12-275c16e4a01b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_RestrictedStockUnitsAndPerformanceShareUnitsMember_019f8f21-7dbb-71be-8504-596b3f6641f1" xlink:href="stx-20260703.xsd#stx_RestrictedStockUnitsAndPerformanceShareUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7dae-98b6-daf47f4b38d2" xlink:to="loc_stx_RestrictedStockUnitsAndPerformanceShareUnitsMember_019f8f21-7dbb-71be-8504-596b3f6641f1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f8f21-7dbb-742e-af26-006bd264088a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-7333-87eb-8f497ce330fa" xlink:to="loc_us-gaap_PlanNameAxis_019f8f21-7dbb-742e-af26-006bd264088a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-742e-af26-006bd264088a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbb-742e-af26-006bd264088a" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-742e-af26-006bd264088a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbb-742e-af26-006bd264088a" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EquityIncentivePlan2012Member_019f8f21-7dbb-7269-8586-e9b9a5caeeba" xlink:href="stx-20260703.xsd#stx_EquityIncentivePlan2012Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_EquityIncentivePlan2012Member_019f8f21-7dbb-7269-8586-e9b9a5caeeba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeagateTechnologyplcStockPurchasePlanMember_019f8f21-7dbb-7503-bb1b-3febcd92ae6b" xlink:href="stx-20260703.xsd#stx_SeagateTechnologyplcStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_SeagateTechnologyplcStockPurchasePlanMember_019f8f21-7dbb-7503-bb1b-3febcd92ae6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_FullValueShareAwardsMember_019f8f21-7dbb-7358-986b-6b7053b829de" xlink:href="stx-20260703.xsd#stx_FullValueShareAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_FullValueShareAwardsMember_019f8f21-7dbb-7358-986b-6b7053b829de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_PerformanceAwardTsrroicMember_019f8f21-7dbb-7f43-976f-dd081ad330f8" xlink:href="stx-20260703.xsd#stx_PerformanceAwardTsrroicMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_PerformanceAwardTsrroicMember_019f8f21-7dbb-7f43-976f-dd081ad330f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NonvestedSharesMember_019f8f21-7dbb-7a8b-9c7a-8297f43df436" xlink:href="stx-20260703.xsd#stx_NonvestedSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_NonvestedSharesMember_019f8f21-7dbb-7a8b-9c7a-8297f43df436" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_PerformanceAwardsMarketConditionMember_019f8f21-7dbb-7b9e-afef-3865de62c8d2" xlink:href="stx-20260703.xsd#stx_PerformanceAwardsMarketConditionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_PerformanceAwardsMarketConditionMember_019f8f21-7dbb-7b9e-afef-3865de62c8d2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_EquityIncentivePlan2022Member_019f8f21-7dbb-7f42-97c9-c57736b3e6d8" xlink:href="stx-20260703.xsd#stx_EquityIncentivePlan2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbb-7457-97b2-1d7ef3a5a1fa" xlink:to="loc_stx_EquityIncentivePlan2022Member_019f8f21-7dbb-7f42-97c9-c57736b3e6d8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019f8f21-7dbb-7bd8-883c-729ceb62b606" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-7333-87eb-8f497ce330fa" xlink:to="loc_us-gaap_VestingAxis_019f8f21-7dbb-7bd8-883c-729ceb62b606" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019f8f21-7dbb-7bd8-883c-729ceb62b606_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_019f8f21-7dbb-7bd8-883c-729ceb62b606" xlink:to="loc_us-gaap_VestingDomain_019f8f21-7dbb-7bd8-883c-729ceb62b606_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019f8f21-7dbb-7eba-b45f-05f88f151bbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_019f8f21-7dbb-7bd8-883c-729ceb62b606" xlink:to="loc_us-gaap_VestingDomain_019f8f21-7dbb-7eba-b45f-05f88f151bbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019f8f21-7dbb-77ac-966d-959aba47e847" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019f8f21-7dbb-7eba-b45f-05f88f151bbb" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019f8f21-7dbb-77ac-966d-959aba47e847" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ShareBasedCompensationAwardTrancheTwoThroughFourMember_019f8f21-7dbb-71df-9eaf-2fb8b0f2dc8a" xlink:href="stx-20260703.xsd#stx_ShareBasedCompensationAwardTrancheTwoThroughFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019f8f21-7dbb-7eba-b45f-05f88f151bbb" xlink:to="loc_stx_ShareBasedCompensationAwardTrancheTwoThroughFourMember_019f8f21-7dbb-71df-9eaf-2fb8b0f2dc8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019f8f21-7dbb-7393-8000-23996eb77400" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019f8f21-7dbb-7393-8000-23996eb77400" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019f8f21-7dbb-7fb6-9253-33cd8721765b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019f8f21-7dbb-7fb6-9253-33cd8721765b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019f8f21-7dbb-7140-9669-4c3eccfeb3e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019f8f21-7dbb-7140-9669-4c3eccfeb3e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SharebasedCompensationArrangementbySharebasedPaymentAwardMaximumNumberofSharesPerOfferingPeriod_019f8f21-7dbb-7f61-81b8-b73729ce3cd1" xlink:href="stx-20260703.xsd#stx_SharebasedCompensationArrangementbySharebasedPaymentAwardMaximumNumberofSharesPerOfferingPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_stx_SharebasedCompensationArrangementbySharebasedPaymentAwardMaximumNumberofSharesPerOfferingPeriod_019f8f21-7dbb-7f61-81b8-b73729ce3cd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_019f8f21-7dbb-7ce2-9df6-eae7fedb90f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_019f8f21-7dbb-7ce2-9df6-eae7fedb90f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ShareBasedCompensationArrangementVestingPeriodMaximum_019f8f21-7dbb-736c-a7fc-9dff8f3799f6" xlink:href="stx-20260703.xsd#stx_ShareBasedCompensationArrangementVestingPeriodMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_stx_ShareBasedCompensationArrangementVestingPeriodMaximum_019f8f21-7dbb-736c-a7fc-9dff8f3799f6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_019f8f21-7dbb-7149-8a2e-a8af8b62527b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_019f8f21-7dbb-7149-8a2e-a8af8b62527b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019f8f21-7dbb-7267-b98a-0807cc8e91a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019f8f21-7dbb-7267-b98a-0807cc8e91a2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ShareBasedCompensationArrangementByShareBasedPaymentAwardRemainingAwardVestingPeriod_019f8f21-7dbb-741f-b39e-d41b65f846d8" xlink:href="stx-20260703.xsd#stx_ShareBasedCompensationArrangementByShareBasedPaymentAwardRemainingAwardVestingPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_stx_ShareBasedCompensationArrangementByShareBasedPaymentAwardRemainingAwardVestingPeriod_019f8f21-7dbb-741f-b39e-d41b65f846d8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceGoalsPeriod_019f8f21-7dbb-7293-9ad7-564eaf4c094d" xlink:href="stx-20260703.xsd#stx_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceGoalsPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_stx_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceGoalsPeriod_019f8f21-7dbb-7293-9ad7-564eaf4c094d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019f8f21-7dbb-76fa-a6d8-79fb563e8662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ShareBasedCompensation_019f8f21-7dbb-76fa-a6d8-79fb563e8662" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_019f8f21-7dbb-7cf3-9bcf-8b34555f8ed0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_019f8f21-7dbb-7cf3-9bcf-8b34555f8ed0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f8f21-7dbb-7996-a29d-dec844b8fd95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f8f21-7dbb-7996-a29d-dec844b8fd95" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f8f21-7dbb-72b1-a040-ec61e1174b9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f8f21-7dbb-72b1-a040-ec61e1174b9c" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_019f8f21-7dbb-70fb-9993-05b54873caac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_019f8f21-7dbb-70fb-9993-05b54873caac" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f8f21-7dbb-7e0c-b9cf-a842952d4175" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f8f21-7dbb-7e0c-b9cf-a842952d4175" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_019f8f21-7dbb-7b93-bb35-3f7b8ba986fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_019f8f21-7dbb-7b93-bb35-3f7b8ba986fe" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_019f8f21-7dbb-7614-88e2-9a5284c2ac72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_019f8f21-7dbb-7614-88e2-9a5284c2ac72" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_019f8f21-7dbb-7855-b3d9-9941cfe3d023" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_019f8f21-7dbb-7855-b3d9-9941cfe3d023" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerShareWeightedAveragePriceOfSharesPurchased_019f8f21-7dbb-7b32-a6bf-37ecbb3e2579" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerShareWeightedAveragePriceOfSharesPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerShareWeightedAveragePriceOfSharesPurchased_019f8f21-7dbb-7b32-a6bf-37ecbb3e2579" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward_019f8f21-7dbb-7ce8-8056-f479f03f48f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward_019f8f21-7dbb-7ce8-8056-f479f03f48f9" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fab00-ee14-7965-ab81-ef74f0848810" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbb-77cc-add8-919a350cae9e" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fab00-ee14-7965-ab81-ef74f0848810" xlink:type="arc" order="21"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/SharebasedCompensationWeightedaverageassumptionsusedtodeterminethefairvalueDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#SharebasedCompensationWeightedaverageassumptionsusedtodeterminethefairvalueDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/SharebasedCompensationWeightedaverageassumptionsusedtodeterminethefairvalueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-74a6-b3d9-af6f81c8187d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-74a6-b3d9-af6f81c8187d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7bcb-a561-b37c6ea8ddf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-74a6-b3d9-af6f81c8187d" xlink:to="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7bcb-a561-b37c6ea8ddf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7bcb-a561-b37c6ea8ddf5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7bcb-a561-b37c6ea8ddf5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-7bcb-a561-b37c6ea8ddf5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-727d-ab1d-01c43ae0b3a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbb-7bcb-a561-b37c6ea8ddf5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-727d-ab1d-01c43ae0b3a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f8f21-7dbb-7426-944a-1ebe895d2347" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-727d-ab1d-01c43ae0b3a7" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f8f21-7dbb-7426-944a-1ebe895d2347" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019f8f21-7dbc-7596-bc88-7ae8bad9404f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-727d-ab1d-01c43ae0b3a7" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019f8f21-7dbc-7596-bc88-7ae8bad9404f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_019f8f21-7dbc-77b6-aa54-8d54f65211be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-727d-ab1d-01c43ae0b3a7" xlink:to="loc_us-gaap_EmployeeStockMember_019f8f21-7dbc-77b6-aa54-8d54f65211be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019f8f21-7dbc-749e-84cf-8dddc0d60751" 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_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbb-727d-ab1d-01c43ae0b3a7" xlink:to="loc_us-gaap_PerformanceSharesMember_019f8f21-7dbc-749e-84cf-8dddc0d60751" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-70bc-9fb9-45fa95853a9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-74a6-b3d9-af6f81c8187d" xlink:to="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-70bc-9fb9-45fa95853a9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-70bc-9fb9-45fa95853a9b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-70bc-9fb9-45fa95853a9b" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-70bc-9fb9-45fa95853a9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7e60-b39b-53c70b7a56d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-70bc-9fb9-45fa95853a9b" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7e60-b39b-53c70b7a56d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SeagateTechnologyplcStockPurchasePlanMember_019f8f21-7dbc-75c8-957d-3b76c73b7b7c" xlink:href="stx-20260703.xsd#stx_SeagateTechnologyplcStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7e60-b39b-53c70b7a56d2" xlink:to="loc_stx_SeagateTechnologyplcStockPurchasePlanMember_019f8f21-7dbc-75c8-957d-3b76c73b7b7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_PerformanceAwardTsrroicMember_019f8f21-7dbc-7f11-9a03-d468f2a01267" xlink:href="stx-20260703.xsd#stx_PerformanceAwardTsrroicMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7e60-b39b-53c70b7a56d2" xlink:to="loc_stx_PerformanceAwardTsrroicMember_019f8f21-7dbc-7f11-9a03-d468f2a01267" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7dbc-719c-8cea-71ce5406d0ee" 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_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbb-74a6-b3d9-af6f81c8187d" xlink:to="loc_srt_RangeAxis_019f8f21-7dbc-719c-8cea-71ce5406d0ee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7dbc-719c-8cea-71ce5406d0ee_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_019f8f21-7dbc-719c-8cea-71ce5406d0ee" xlink:to="loc_srt_RangeMember_019f8f21-7dbc-719c-8cea-71ce5406d0ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7dbc-7099-92a6-e1284519a4f7" 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_019f8f21-7dbc-719c-8cea-71ce5406d0ee" xlink:to="loc_srt_RangeMember_019f8f21-7dbc-7099-92a6-e1284519a4f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7dbc-7c86-b4e7-75d3b3385857" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7dbc-7099-92a6-e1284519a4f7" xlink:to="loc_srt_MinimumMember_019f8f21-7dbc-7c86-b4e7-75d3b3385857" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7dbc-7626-95f7-f7d9936a2416" 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_019f8f21-7dbc-7099-92a6-e1284519a4f7" xlink:to="loc_srt_MaximumMember_019f8f21-7dbc-7626-95f7-f7d9936a2416" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019f8f21-7dbc-7cc9-8518-b8540b9781e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019f8f21-7dbc-7cc9-8518-b8540b9781e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019f8f21-7dbc-74a2-b119-67603e57a00d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019f8f21-7dbc-74a2-b119-67603e57a00d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsWeightedAverageExpectedDividendRate_019f8f21-7dbc-7386-93d0-2f040e7f5adf" xlink:href="stx-20260703.xsd#stx_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsWeightedAverageExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_stx_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsWeightedAverageExpectedDividendRate_019f8f21-7dbc-7386-93d0-2f040e7f5adf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-7c75-9b6e-994271215658" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-7c75-9b6e-994271215658" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019f8f21-7dbc-709d-87e3-af91ee4130b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019f8f21-7dbc-709d-87e3-af91ee4130b1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_019f8f21-7dbc-719c-a895-4a9e8e513860" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_019f8f21-7dbc-719c-a895-4a9e8e513860" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019f8f21-7dbc-7e2a-a68d-c71067b608d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-713b-a96f-7e58707839f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019f8f21-7dbc-7e2a-a68d-c71067b608d1" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/SharebasedCompensationNonvestedshareactivityDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#SharebasedCompensationNonvestedshareactivityDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/SharebasedCompensationNonvestedshareactivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-714e-a7e5-0b405031f426" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-78ba-8b1d-38495c7ae7bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-714e-a7e5-0b405031f426" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-78ba-8b1d-38495c7ae7bb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7c91-b1b0-1e8de25db0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-78ba-8b1d-38495c7ae7bb" xlink:to="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7c91-b1b0-1e8de25db0bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7c91-b1b0-1e8de25db0bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7c91-b1b0-1e8de25db0bb" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7c91-b1b0-1e8de25db0bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-790c-9347-7034177aaa91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7c91-b1b0-1e8de25db0bb" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-790c-9347-7034177aaa91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_NonvestedSharesMember_019f8f21-7dbc-7e3c-9f6e-db8730d94bf8" xlink:href="stx-20260703.xsd#stx_NonvestedSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-790c-9347-7034177aaa91" xlink:to="loc_stx_NonvestedSharesMember_019f8f21-7dbc-7e3c-9f6e-db8730d94bf8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-725e-b62f-91050f3c24a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-78ba-8b1d-38495c7ae7bb" xlink:to="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-725e-b62f-91050f3c24a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-725e-b62f-91050f3c24a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-725e-b62f-91050f3c24a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-725e-b62f-91050f3c24a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-72b8-8dc4-83009e9f959c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-725e-b62f-91050f3c24a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-72b8-8dc4-83009e9f959c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019f8f21-7dbc-7998-b826-a97de814da1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-72b8-8dc4-83009e9f959c" xlink:to="loc_us-gaap_StockCompensationPlanMember_019f8f21-7dbc-7998-b826-a97de814da1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-7c72-ae2b-8aa6a7072070" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-714e-a7e5-0b405031f426" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-7c72-ae2b-8aa6a7072070" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019f8f21-7dbc-7bee-ae02-b1bb6adcb93b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-7c72-ae2b-8aa6a7072070" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019f8f21-7dbc-7bee-ae02-b1bb6adcb93b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019f8f21-7dbc-770b-97f1-c60ff56b4c13" 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_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-7c72-ae2b-8aa6a7072070" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019f8f21-7dbc-770b-97f1-c60ff56b4c13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019f8f21-7dbc-73be-9975-36e2c0bd4b77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-7c72-ae2b-8aa6a7072070" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019f8f21-7dbc-73be-9975-36e2c0bd4b77" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019f8f21-7dbc-79dd-b401-eaa937b1fdcf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-7c72-ae2b-8aa6a7072070" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019f8f21-7dbc-79dd-b401-eaa937b1fdcf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019f8f21-7dbc-762b-b168-a85e39fddd8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-79ed-8a3d-fb51ae973532" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-714e-a7e5-0b405031f426" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-79ed-8a3d-fb51ae973532" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019f8f21-7dbc-7d42-ac60-0574461127bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-79ed-8a3d-fb51ae973532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019f8f21-7dbc-7d42-ac60-0574461127bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-7bdc-935b-83051fb75290" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-79ed-8a3d-fb51ae973532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-7bdc-935b-83051fb75290" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019f8f21-7dbc-7456-93a2-f02b976b9242" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-79ed-8a3d-fb51ae973532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019f8f21-7dbc-7456-93a2-f02b976b9242" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-728f-a796-e7cb220d3464" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-79ed-8a3d-fb51ae973532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-728f-a796-e7cb220d3464" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019f8f21-7dbc-77a1-b24a-464a2df54b32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/SharebasedCompensationPerformanceawardactivityDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#SharebasedCompensationPerformanceawardactivityDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/SharebasedCompensationPerformanceawardactivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-7841-8651-3ff1a7c09bec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-7155-89e6-2de3b298d577" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-7841-8651-3ff1a7c09bec" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-7155-89e6-2de3b298d577" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-7726-ae4d-30038f7c4720" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-7155-89e6-2de3b298d577" xlink:to="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-7726-ae4d-30038f7c4720" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-7726-ae4d-30038f7c4720_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-7726-ae4d-30038f7c4720" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-7726-ae4d-30038f7c4720_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-7b36-97a1-4be3b83942b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f8f21-7dbc-7726-ae4d-30038f7c4720" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-7b36-97a1-4be3b83942b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019f8f21-7dbc-7b8f-a777-62ba438efb71" 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_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8f21-7dbc-7b36-97a1-4be3b83942b7" xlink:to="loc_us-gaap_PerformanceSharesMember_019f8f21-7dbc-7b8f-a777-62ba438efb71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7509-a0e1-cfadfb578c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f8f21-7dbc-7155-89e6-2de3b298d577" xlink:to="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7509-a0e1-cfadfb578c1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7509-a0e1-cfadfb578c1a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7509-a0e1-cfadfb578c1a" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7509-a0e1-cfadfb578c1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7848-a406-9f17f7434cb6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f8f21-7dbc-7509-a0e1-cfadfb578c1a" xlink:to="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7848-a406-9f17f7434cb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_PerformanceAwardsMarketConditionMember_019f8f21-7dbc-7f25-b3de-039f17be637d" xlink:href="stx-20260703.xsd#stx_PerformanceAwardsMarketConditionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f8f21-7dbc-7848-a406-9f17f7434cb6" xlink:to="loc_stx_PerformanceAwardsMarketConditionMember_019f8f21-7dbc-7f25-b3de-039f17be637d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-766f-a9c7-0f99b37286a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-7841-8651-3ff1a7c09bec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-766f-a9c7-0f99b37286a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019f8f21-7dbc-7f30-9202-62d1a4196b25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-766f-a9c7-0f99b37286a5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019f8f21-7dbc-7f30-9202-62d1a4196b25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019f8f21-7dbc-70f4-af34-1f3d297b5730" 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_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-766f-a9c7-0f99b37286a5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019f8f21-7dbc-70f4-af34-1f3d297b5730" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019f8f21-7dbc-7d98-bb17-68b2b8ce9574" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-766f-a9c7-0f99b37286a5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019f8f21-7dbc-7d98-bb17-68b2b8ce9574" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019f8f21-7dbc-7a13-8f51-31992b3b95e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019f8f21-7dbc-766f-a9c7-0f99b37286a5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019f8f21-7dbc-7a13-8f51-31992b3b95e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019f8f21-7dbc-7886-8cab-3abbf96fc80e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-7535-92bf-3460241d87d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f8f21-7dbc-7841-8651-3ff1a7c09bec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-7535-92bf-3460241d87d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019f8f21-7dbc-750f-970b-07de5b87da29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-7535-92bf-3460241d87d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019f8f21-7dbc-750f-970b-07de5b87da29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-74c7-ae79-29a05aee5ef8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-7535-92bf-3460241d87d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-74c7-ae79-29a05aee5ef8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019f8f21-7dbc-77d4-88c5-f2e19068e79c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-7535-92bf-3460241d87d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019f8f21-7dbc-77d4-88c5-f2e19068e79c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-7286-8b80-682025433faa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019f8f21-7dbc-7535-92bf-3460241d87d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019f8f21-7dbc-7286-8b80-682025433faa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019f8f21-7dbc-7422-925c-551fd6abb023" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/GuaranteesNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#GuaranteesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/GuaranteesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7dbc-7765-a701-b55b9ef9a019" xlink:href="stx-20260703.xsd#stx_ScheduleOfFiscalYearsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7dbc-7e96-845d-4f678b37abb3" xlink:href="stx-20260703.xsd#stx_ScheduleofFiscalYearsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7dbc-7765-a701-b55b9ef9a019" xlink:to="loc_stx_ScheduleofFiscalYearsTable_019f8f21-7dbc-7e96-845d-4f678b37abb3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f8f21-7dbc-77c1-99be-dfc4a5c6ca87" 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_stx_ScheduleofFiscalYearsTable_019f8f21-7dbc-7e96-845d-4f678b37abb3" xlink:to="loc_srt_RangeAxis_019f8f21-7dbc-77c1-99be-dfc4a5c6ca87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7dbc-77c1-99be-dfc4a5c6ca87_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_019f8f21-7dbc-77c1-99be-dfc4a5c6ca87" xlink:to="loc_srt_RangeMember_019f8f21-7dbc-77c1-99be-dfc4a5c6ca87_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f8f21-7dbc-775c-bf4c-560aa20dc1d5" 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_019f8f21-7dbc-77c1-99be-dfc4a5c6ca87" xlink:to="loc_srt_RangeMember_019f8f21-7dbc-775c-bf4c-560aa20dc1d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f8f21-7dbc-74a6-ad57-2dc7744bed68" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f8f21-7dbc-775c-bf4c-560aa20dc1d5" xlink:to="loc_srt_MinimumMember_019f8f21-7dbc-74a6-ad57-2dc7744bed68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f8f21-7dbc-77db-b1a7-afff1dffb6f8" 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_019f8f21-7dbc-775c-bf4c-560aa20dc1d5" xlink:to="loc_srt_MaximumMember_019f8f21-7dbc-77db-b1a7-afff1dffb6f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_IndemnificationsobligationstoOfficersandDirectors_019f8f21-7dbc-7abb-a894-8864f78eafb5" xlink:href="stx-20260703.xsd#stx_IndemnificationsobligationstoOfficersandDirectors"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7dbc-7765-a701-b55b9ef9a019" xlink:to="loc_stx_IndemnificationsobligationstoOfficersandDirectors_019f8f21-7dbc-7abb-a894-8864f78eafb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Intellectualpropertyindemnificationobligations_019f8f21-7dbc-79f3-95b2-6002476c1acf" xlink:href="stx-20260703.xsd#stx_Intellectualpropertyindemnificationobligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7dbc-7765-a701-b55b9ef9a019" xlink:to="loc_stx_Intellectualpropertyindemnificationobligations_019f8f21-7dbc-79f3-95b2-6002476c1acf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7dbc-777b-932c-bec452ae1914" xlink:href="stx-20260703.xsd#stx_ProductWarrantyPeriodTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7dbc-7765-a701-b55b9ef9a019" xlink:to="loc_stx_ProductWarrantyPeriodTerm_019f8f21-7dbc-777b-932c-bec452ae1914" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrual_019f8f21-7dbc-7794-82be-ab9ad401a5ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StandardProductWarrantyAccrual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_stx_ScheduleOfFiscalYearsLineItems_019f8f21-7dbc-7765-a701-b55b9ef9a019" xlink:to="loc_us-gaap_StandardProductWarrantyAccrual_019f8f21-7dbc-7794-82be-ab9ad401a5ad" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/LegalEnvironmentalandOtherContingenciesDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#LegalEnvironmentalandOtherContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/LegalEnvironmentalandOtherContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019f947d-f6fd-7a9d-bc23-965b8560a1be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_us-gaap_LossContingenciesTable_019f947d-f6fd-7a9d-bc23-965b8560a1be" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f947d-f6fd-730a-aeb0-3319f23bfb31" 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_LossContingenciesTable_019f947d-f6fd-7a9d-bc23-965b8560a1be" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f947d-f6fd-730a-aeb0-3319f23bfb31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementAmount_019f947d-f6fd-70c4-98d9-dda7a8613bbe" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementAmount_019f947d-f6fd-70c4-98d9-dda7a8613bbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementQuarterlyInstallmentsAmount_019f947d-f6fd-734b-b731-4caec587c427" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementQuarterlyInstallmentsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementQuarterlyInstallmentsAmount_019f947d-f6fd-734b-b731-4caec587c427" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementTermsPeriodOfPayments_019f947d-f6fd-77e8-9a27-c8806615d98b" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementTermsPeriodOfPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementTermsPeriodOfPayments_019f947d-f6fd-77e8-9a27-c8806615d98b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementNumberOfAudits_019f947d-f6fd-74eb-89cb-7c2844622abc" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementNumberOfAudits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementNumberOfAudits_019f947d-f6fd-74eb-89cb-7c2844622abc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementNumberOfInternalAudits_019f947d-f6fd-72ac-b3db-0663dcafbbfd" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementNumberOfInternalAudits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementNumberOfInternalAudits_019f947d-f6fd-72ac-b3db-0663dcafbbfd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LitigationSettlementNumberOfInternalAudits_019f947d-f6fd-7091-8893-8641266f2b42" xlink:href="stx-20260703.xsd#stx_LitigationSettlementNumberOfInternalAudits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LitigationSettlementNumberOfInternalAudits_019f947d-f6fd-7091-8893-8641266f2b42" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyLossInPeriod_019f947d-f6fd-7fbd-aa03-d347a631bb9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyLossInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_us-gaap_LossContingencyLossInPeriod_019f947d-f6fd-7fbd-aa03-d347a631bb9f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f947d-f6fd-7c6d-8beb-6ef9af93eef9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f947d-f6fd-7c6d-8beb-6ef9af93eef9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_IncreaseDecreaseInAccrualForLossContingency_019f947d-f6fd-720d-a4ab-260e4a7b81d1" xlink:href="stx-20260703.xsd#stx_IncreaseDecreaseInAccrualForLossContingency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_IncreaseDecreaseInAccrualForLossContingency_019f947d-f6fd-720d-a4ab-260e4a7b81d1" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/LegalEnvironmentalandOtherContingenciesDetails_1" xlink:type="simple" xlink:href="stx-20260703.xsd#LegalEnvironmentalandOtherContingenciesDetails_1"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/LegalEnvironmentalandOtherContingenciesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019f947d-f6fd-7a9d-bc23-965b8560a1be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_us-gaap_LossContingenciesTable_019f947d-f6fd-7a9d-bc23-965b8560a1be" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementAmount_019f947d-f6fd-70c4-98d9-dda7a8613bbe" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementAmount_019f947d-f6fd-70c4-98d9-dda7a8613bbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementQuarterlyInstallmentsAmount_019f947d-f6fd-734b-b731-4caec587c427" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementQuarterlyInstallmentsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementQuarterlyInstallmentsAmount_019f947d-f6fd-734b-b731-4caec587c427" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementTermsPeriodOfPayments_019f947d-f6fd-77e8-9a27-c8806615d98b" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementTermsPeriodOfPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementTermsPeriodOfPayments_019f947d-f6fd-77e8-9a27-c8806615d98b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementNumberOfAudits_019f947d-f6fd-74eb-89cb-7c2844622abc" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementNumberOfAudits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementNumberOfAudits_019f947d-f6fd-74eb-89cb-7c2844622abc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LossContingencySettlementNumberOfInternalAudits_019f947d-f6fd-72ac-b3db-0663dcafbbfd" xlink:href="stx-20260703.xsd#stx_LossContingencySettlementNumberOfInternalAudits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LossContingencySettlementNumberOfInternalAudits_019f947d-f6fd-72ac-b3db-0663dcafbbfd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_LitigationSettlementNumberOfInternalAudits_019f947d-f6fd-7091-8893-8641266f2b42" xlink:href="stx-20260703.xsd#stx_LitigationSettlementNumberOfInternalAudits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_LitigationSettlementNumberOfInternalAudits_019f947d-f6fd-7091-8893-8641266f2b42" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyLossInPeriod_019f947d-f6fd-7fbd-aa03-d347a631bb9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyLossInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_us-gaap_LossContingencyLossInPeriod_019f947d-f6fd-7fbd-aa03-d347a631bb9f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f947d-f6fd-7c6d-8beb-6ef9af93eef9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f947d-f6fd-7c6d-8beb-6ef9af93eef9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_IncreaseDecreaseInAccrualForLossContingency_019f947d-f6fd-720d-a4ab-260e4a7b81d1" xlink:href="stx-20260703.xsd#stx_IncreaseDecreaseInAccrualForLossContingency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f947d-f6fd-72b4-abef-6c2c17731cf5" xlink:to="loc_stx_IncreaseDecreaseInAccrualForLossContingency_019f947d-f6fd-720d-a4ab-260e4a7b81d1" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/CommitmentsNarrativeDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#CommitmentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/CommitmentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RecordedUnconditionalPurchaseObligationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RecordedUnconditionalPurchaseObligationTable_019f8f21-7dbc-7cc1-8dc5-e324416135a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RecordedUnconditionalPurchaseObligationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:to="loc_us-gaap_RecordedUnconditionalPurchaseObligationTable_019f8f21-7dbc-7cc1-8dc5-e324416135a1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019f8f21-7dbc-7029-89a5-1b91ab1a6ad5" 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_RecordedUnconditionalPurchaseObligationTable_019f8f21-7dbc-7cc1-8dc5-e324416135a1" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019f8f21-7dbc-7029-89a5-1b91ab1a6ad5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f8f21-7dbc-7029-89a5-1b91ab1a6ad5_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_019f8f21-7dbc-7029-89a5-1b91ab1a6ad5" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f8f21-7dbc-7029-89a5-1b91ab1a6ad5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f8f21-7dbc-7356-b561-a01576b9ff51" 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_019f8f21-7dbc-7029-89a5-1b91ab1a6ad5" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f8f21-7dbc-7356-b561-a01576b9ff51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoriesMember_019f8f21-7dbc-7b99-82b6-da7b9239da1c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f8f21-7dbc-7356-b561-a01576b9ff51" xlink:to="loc_us-gaap_InventoriesMember_019f8f21-7dbc-7b99-82b6-da7b9239da1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalAdditionsMember_019f8f21-7dbc-7e70-9162-bce0cd13aa0e" 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_019f8f21-7dbc-7356-b561-a01576b9ff51" xlink:to="loc_us-gaap_CapitalAdditionsMember_019f8f21-7dbc-7e70-9162-bce0cd13aa0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019f8f21-7dbc-7968-b5ad-14a84e09f3f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019f8f21-7dbc-7968-b5ad-14a84e09f3f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary_019f8f21-7dbc-7ac5-9d38-d12b95d9dc01" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary_019f8f21-7dbc-7ac5-9d38-d12b95d9dc01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary_019f8f21-7dbc-7304-abf4-04d9108c7976" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary_019f8f21-7dbc-7304-abf4-04d9108c7976" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary_019f8f21-7dbc-7852-9cc2-7d50abcc0675" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary_019f8f21-7dbc-7852-9cc2-7d50abcc0675" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary_019f8f21-7dbc-7b68-9f0c-9ff197dbef15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019f8f21-7dbc-7f32-b004-ed1004fdc71c" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary_019f8f21-7dbc-7b68-9f0c-9ff197dbef15" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/BusinessSegmentandGeographicInformationScheduleofRevenuefromExternalCustomersandLongLivedAssetsbyGeographicalAreasDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#BusinessSegmentandGeographicInformationScheduleofRevenuefromExternalCustomersandLongLivedAssetsbyGeographicalAreasDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/BusinessSegmentandGeographicInformationScheduleofRevenuefromExternalCustomersandLongLivedAssetsbyGeographicalAreasDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f8f21-7dbc-7495-b204-99cd19431504" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019f8f21-7dbc-726b-b015-84c93db7ab7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f8f21-7dbc-7495-b204-99cd19431504" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019f8f21-7dbc-726b-b015-84c93db7ab7b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74ac-8899-b9c4b87d19ac" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019f8f21-7dbc-726b-b015-84c93db7ab7b" xlink:to="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74ac-8899-b9c4b87d19ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-74ac-8899-b9c4b87d19ac_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74ac-8899-b9c4b87d19ac" xlink:to="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-74ac-8899-b9c4b87d19ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74ac-8899-b9c4b87d19ac" xlink:to="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SG_019f8f21-7dbc-773d-a0e6-446236ce42cc" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_SG"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:to="loc_country_SG_019f8f21-7dbc-773d-a0e6-446236ce42cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019f8f21-7dbc-793b-a480-893b1292ff01" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:to="loc_country_US_019f8f21-7dbc-793b-a480-893b1292ff01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_NL_019f8f21-7dbc-7551-bec6-51340da40f9e" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_NL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:to="loc_country_NL_019f8f21-7dbc-7551-bec6-51340da40f9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OtherCountriesMember_019f8f21-7dbc-7f41-9b7c-0c9bfd99dd79" xlink:href="stx-20260703.xsd#stx_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:to="loc_stx_OtherCountriesMember_019f8f21-7dbc-7f41-9b7c-0c9bfd99dd79" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_TH_019f8f21-7dbc-7f8b-a23b-f5b5532f08ac" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_TH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:to="loc_country_TH_019f8f21-7dbc-7f8b-a23b-f5b5532f08ac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_019f8f21-7dbc-78e0-837f-e9d3d3ab9a14" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-78a4-b518-3100e6475f7e" xlink:to="loc_country_GB_019f8f21-7dbc-78e0-837f-e9d3d3ab9a14" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_019f8f21-7dbc-7dc1-b12b-8f78a3f604de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f8f21-7dbc-7495-b204-99cd19431504" xlink:to="loc_us-gaap_NoncurrentAssets_019f8f21-7dbc-7dc1-b12b-8f78a3f604de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019f8f21-7dbc-741e-9ac3-83b66633aa7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f8f21-7dbc-7495-b204-99cd19431504" xlink:to="loc_us-gaap_NumberOfReportableSegments_019f8f21-7dbc-741e-9ac3-83b66633aa7c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/RevenueDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#RevenueDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/RevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019f8f21-7dbc-7e48-b524-09da760a9af8" 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_019f8f21-7dbc-7071-8f73-7163645dd893" 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_019f8f21-7dbc-7e48-b524-09da760a9af8" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019f8f21-7dbc-7071-8f73-7163645dd893" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019f8f21-7dbc-78f4-b26c-f842e28780f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f8f21-7dbc-7071-8f73-7163645dd893" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019f8f21-7dbc-78f4-b26c-f842e28780f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-78f4-b26c-f842e28780f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019f8f21-7dbc-78f4-b26c-f842e28780f7" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-78f4-b26c-f842e28780f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-76e8-8cd1-8e21aa4853ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019f8f21-7dbc-78f4-b26c-f842e28780f7" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-76e8-8cd1-8e21aa4853ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OEMsMember_019f8f21-7dbc-7375-ab4c-25c6b879d2b6" xlink:href="stx-20260703.xsd#stx_OEMsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-76e8-8cd1-8e21aa4853ff" xlink:to="loc_stx_OEMsMember_019f8f21-7dbc-7375-ab4c-25c6b879d2b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DistributorsMember_019f8f21-7dbc-7f31-a34f-f2bfc40a82e0" xlink:href="stx-20260703.xsd#stx_DistributorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-76e8-8cd1-8e21aa4853ff" xlink:to="loc_stx_DistributorsMember_019f8f21-7dbc-7f31-a34f-f2bfc40a82e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetailMember_019f8f21-7dbc-7df3-9271-8e2d8d18ae16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019f8f21-7dbc-76e8-8cd1-8e21aa4853ff" xlink:to="loc_us-gaap_RetailMember_019f8f21-7dbc-7df3-9271-8e2d8d18ae16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f8f21-7dbc-7138-ad62-51ee8c37db32" 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_019f8f21-7dbc-7071-8f73-7163645dd893" xlink:to="loc_srt_MajorCustomersAxis_019f8f21-7dbc-7138-ad62-51ee8c37db32" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f8f21-7dbc-7138-ad62-51ee8c37db32_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_019f8f21-7dbc-7138-ad62-51ee8c37db32" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f8f21-7dbc-7138-ad62-51ee8c37db32_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f8f21-7dbc-7c5f-b662-515847a82564" 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_019f8f21-7dbc-7138-ad62-51ee8c37db32" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f8f21-7dbc-7c5f-b662-515847a82564" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OneCustomerMember_019f8f21-7dbc-75e2-922e-cbe83008b929" xlink:href="stx-20260703.xsd#stx_OneCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f8f21-7dbc-7c5f-b662-515847a82564" xlink:to="loc_stx_OneCustomerMember_019f8f21-7dbc-75e2-922e-cbe83008b929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74c4-9e03-a2c33d9ced5d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f8f21-7dbc-7071-8f73-7163645dd893" xlink:to="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74c4-9e03-a2c33d9ced5d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-74c4-9e03-a2c33d9ced5d_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74c4-9e03-a2c33d9ced5d" xlink:to="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-74c4-9e03-a2c33d9ced5d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-70fd-b652-8454c9d4e158" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019f8f21-7dbc-74c4-9e03-a2c33d9ced5d" xlink:to="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-70fd-b652-8454c9d4e158" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SG_019f8f21-7dbc-7cd2-8e47-f73422d47304" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_SG"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-70fd-b652-8454c9d4e158" xlink:to="loc_country_SG_019f8f21-7dbc-7cd2-8e47-f73422d47304" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019f8f21-7dbc-7970-817b-d06c3bf03d3e" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-70fd-b652-8454c9d4e158" xlink:to="loc_country_US_019f8f21-7dbc-7970-817b-d06c3bf03d3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_NL_019f8f21-7dbc-749d-8648-4378ec9eab80" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_NL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-70fd-b652-8454c9d4e158" xlink:to="loc_country_NL_019f8f21-7dbc-749d-8648-4378ec9eab80" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_OtherCountriesMember_019f8f21-7dbc-785e-94c5-3c2706a44d89" xlink:href="stx-20260703.xsd#stx_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f8f21-7dbc-70fd-b652-8454c9d4e158" xlink:to="loc_stx_OtherCountriesMember_019f8f21-7dbc-785e-94c5-3c2706a44d89" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f8f21-7dbc-769d-8fc3-120224f7c6c4" 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_019f8f21-7dbc-7e48-b524-09da760a9af8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f8f21-7dbc-769d-8fc3-120224f7c6c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f8f21-7dbc-73ba-90ef-5a9d7d64d6fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019f8f21-7dbc-7e48-b524-09da760a9af8" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f8f21-7dbc-73ba-90ef-5a9d7d64d6fc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/DivestureDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#DivestureDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/DivestureDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" 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_019f8f21-7dbc-7230-8466-fdee5a211924" 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_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f8f21-7dbc-7230-8466-fdee5a211924" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019f8f21-7dbc-7a34-b052-ba2421a18b4c" 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_019f8f21-7dbc-7230-8466-fdee5a211924" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019f8f21-7dbc-7a34-b052-ba2421a18b4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7dbc-7a34-b052-ba2421a18b4c_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_019f8f21-7dbc-7a34-b052-ba2421a18b4c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7dbc-7a34-b052-ba2421a18b4c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7dbc-7167-8d13-68182b876ebf" 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_019f8f21-7dbc-7a34-b052-ba2421a18b4c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7dbc-7167-8d13-68182b876ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019f8f21-7dbc-7638-bd4c-8e567a81ab6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019f8f21-7dbc-7167-8d13-68182b876ebf" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019f8f21-7dbc-7638-bd4c-8e567a81ab6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019f8f21-7dbc-7e37-a275-335bf5c210ae" 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_019f8f21-7dbc-7230-8466-fdee5a211924" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019f8f21-7dbc-7e37-a275-335bf5c210ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8f21-7dbc-7e37-a275-335bf5c210ae_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_019f8f21-7dbc-7e37-a275-335bf5c210ae" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8f21-7dbc-7e37-a275-335bf5c210ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8f21-7dbc-7e12-bf5d-06366ac92b5b" 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_019f8f21-7dbc-7e37-a275-335bf5c210ae" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8f21-7dbc-7e12-bf5d-06366ac92b5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_SoCOperationsMember_019f8f21-7dbc-7988-b392-bc65ab470902" xlink:href="stx-20260703.xsd#stx_SoCOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8f21-7dbc-7e12-bf5d-06366ac92b5b" xlink:to="loc_stx_SoCOperationsMember_019f8f21-7dbc-7988-b392-bc65ab470902" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7dbc-75c1-a01f-bd12b6bebd9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f8f21-7dbc-7230-8466-fdee5a211924" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7dbc-75c1-a01f-bd12b6bebd9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7dbc-75c1-a01f-bd12b6bebd9b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7dbc-75c1-a01f-bd12b6bebd9b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7dbc-75c1-a01f-bd12b6bebd9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7dbc-72fd-bdec-ec65ffb1c74b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f8f21-7dbc-75c1-a01f-bd12b6bebd9b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7dbc-72fd-bdec-ec65ffb1c74b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_IntevacInc.Member_019f8f21-7dbc-70d3-9b7b-e1cc80c8b44a" xlink:href="stx-20260703.xsd#stx_IntevacInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8f21-7dbc-72fd-bdec-ec65ffb1c74b" xlink:to="loc_stx_IntevacInc.Member_019f8f21-7dbc-70d3-9b7b-e1cc80c8b44a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f8f21-7dbc-7132-94cc-841d0cab94e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f8f21-7dbc-7132-94cc-841d0cab94e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTangibleAssetsNet_019f8f21-7dbc-744f-b1f8-bf211a734682" xlink:href="stx-20260703.xsd#stx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_stx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTangibleAssetsNet_019f8f21-7dbc-744f-b1f8-bf211a734682" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019f8f21-7dbc-7f04-8762-40b8df670fce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019f8f21-7dbc-7f04-8762-40b8df670fce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f8f21-7dbc-7509-8fa4-acb3559a8235" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_Goodwill_019f8f21-7dbc-7509-8fa4-acb3559a8235" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019f8f21-7dbc-799d-8d88-2602ba84c02c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019f8f21-7dbc-799d-8d88-2602ba84c02c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DisposalGroupIncludingDiscontinuedOperationConsiderationGross_019f8f21-7dbc-7a01-a6b2-16afc24a04c0" xlink:href="stx-20260703.xsd#stx_DisposalGroupIncludingDiscontinuedOperationConsiderationGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_stx_DisposalGroupIncludingDiscontinuedOperationConsiderationGross_019f8f21-7dbc-7a01-a6b2-16afc24a04c0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_019f8f21-7dbc-7fed-9d1e-dc9cd66a36a9" 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_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_019f8f21-7dbc-7fed-9d1e-dc9cd66a36a9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DisposalGroupIncludingDiscontinuedOperationConsiderationIndemnificationReceivable_019f8f21-7dbc-717e-b111-dc14ffce703b" xlink:href="stx-20260703.xsd#stx_DisposalGroupIncludingDiscontinuedOperationConsiderationIndemnificationReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_stx_DisposalGroupIncludingDiscontinuedOperationConsiderationIndemnificationReceivable_019f8f21-7dbc-717e-b111-dc14ffce703b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_DisposalGroupIncludingDiscontinuedOperationConsiderationIndemnificationReceivableCurrent_019f8f21-7dbc-7ad3-90d5-4809cb1aa569" xlink:href="stx-20260703.xsd#stx_DisposalGroupIncludingDiscontinuedOperationConsiderationIndemnificationReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_stx_DisposalGroupIncludingDiscontinuedOperationConsiderationIndemnificationReceivableCurrent_019f8f21-7dbc-7ad3-90d5-4809cb1aa569" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019f8f21-7dbc-7523-8f36-5a735fdebcd8" 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_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019f8f21-7dbc-7523-8f36-5a735fdebcd8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_019f8f21-7dbc-7b7f-b66f-051e1a3af98c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_019f8f21-7dbc-7b7f-b66f-051e1a3af98c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_019f8f21-7dbc-72fa-8f74-5200f5cfe25a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_019f8f21-7dbc-72fa-8f74-5200f5cfe25a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_019f8f21-7dbc-70a1-b159-1f70cd922eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8f21-7dbc-7aab-baff-63f4c5bbfe8c" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_019f8f21-7dbc-70a1-b159-1f70cd922eb7" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.seagate.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="stx-20260703.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.seagate.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019f8f21-7dbc-7f2e-ab7e-7c26916eae15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019f8f21-7dbc-7ab4-9cc2-fa8371f2d4ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f8f21-7dbc-7f2e-ab7e-7c26916eae15" xlink:to="loc_us-gaap_SubsequentEventTable_019f8f21-7dbc-7ab4-9cc2-fa8371f2d4ac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f8f21-7dbc-701e-aa42-05102556c24d" 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_SubsequentEventTable_019f8f21-7dbc-7ab4-9cc2-fa8371f2d4ac" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f8f21-7dbc-701e-aa42-05102556c24d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f8f21-7dbc-701e-aa42-05102556c24d_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_019f8f21-7dbc-701e-aa42-05102556c24d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f8f21-7dbc-701e-aa42-05102556c24d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f8f21-7dbc-7653-abab-055d44da04b3" 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_019f8f21-7dbc-701e-aa42-05102556c24d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f8f21-7dbc-7653-abab-055d44da04b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f8f21-7dbc-7aa1-bab3-e3ef29790cce" 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_019f8f21-7dbc-7653-abab-055d44da04b3" xlink:to="loc_us-gaap_SubsequentEventMember_019f8f21-7dbc-7aa1-bab3-e3ef29790cce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_019f8f21-7dbc-7637-82cf-409dd26cef85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019f8f21-7dbc-7f2e-ab7e-7c26916eae15" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_019f8f21-7dbc-7637-82cf-409dd26cef85" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/srt/role/srt-eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-roles-2026.xsd#eedm1"/>
  <link:definitionLink xlink:role="http://fasb.org/srt/role/srt-eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense" xlink:type="arc" order="691"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:type="arc" order="101"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" 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_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="102"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent" 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_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsCurrent" xlink:type="arc" order="103"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent" 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_LiabilitiesAbstract" xlink:to="loc_us-gaap_AccountsPayableCurrent" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:type="arc" order="41"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_Dr.JohnC.MorrisMember_019f8f21-7b22-7278-be95-8f1c8ddee8ba" xlink:href="stx-20260703.xsd#stx_Dr.JohnC.MorrisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_stx_Dr.JohnC.MorrisMember_019f8f21-7b22-7278-be95-8f1c8ddee8ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_PratS.BhattMember_019f945f-20ec-7abc-b7a7-bffdeb41e611" xlink:href="stx-20260703.xsd#stx_PratS.BhattMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_stx_PratS.BhattMember_019f945f-20ec-7abc-b7a7-bffdeb41e611" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stx_GianlucaRomanoMember_019f8f21-7b22-7ffd-9f86-6c0b97398a64" xlink:href="stx-20260703.xsd#stx_GianlucaRomanoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_stx_GianlucaRomanoMember_019f8f21-7b22-7ffd-9f86-6c0b97398a64" xlink:type="arc" order="4"/>
  </link:definitionLink>
</link:linkbase>
