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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e69cb-5f1a-7b67-adef-a80eefdfdf72,g:fc29e5c0-29a6-4de8-8fd8-608caa10ae95-->
<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.talenenergy.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="simple" xlink:href="tln-20260630.xsd#CondensedConsolidatedStatementsOfOperationsUnaudited"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" 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_019e69cb-63b5-7a9c-8515-87dfb503d860" 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_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_StatementTable_019e69cb-63b5-7a9c-8515-87dfb503d860" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e69cb-63b5-71d4-a15b-2252b56c985c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e69cb-63b5-7a9c-8515-87dfb503d860" xlink:to="loc_srt_ProductOrServiceAxis_019e69cb-63b5-71d4-a15b-2252b56c985c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-71d4-a15b-2252b56c985c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-63b5-71d4-a15b-2252b56c985c" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-71d4-a15b-2252b56c985c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-7df9-be3c-6e5accb875a5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-63b5-71d4-a15b-2252b56c985c" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-7df9-be3c-6e5accb875a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnergyAndOtherMember_019e69cb-63b5-7307-ba5f-72eb747898e4" xlink:href="tln-20260630.xsd#tln_EnergyAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-7df9-be3c-6e5accb875a5" xlink:to="loc_tln_EnergyAndOtherMember_019e69cb-63b5-7307-ba5f-72eb747898e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenueCapacityMember_019e69cb-63b5-79d5-8e23-c1e0fba23357" xlink:href="tln-20260630.xsd#tln_OperatingRevenueCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-7df9-be3c-6e5accb875a5" xlink:to="loc_tln_OperatingRevenueCapacityMember_019e69cb-63b5-79d5-8e23-c1e0fba23357" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CommodityContractsUnrealizedGainLossMember_019e69cb-63b5-7767-92b8-d2b13b87522a" xlink:href="tln-20260630.xsd#tln_CommodityContractsUnrealizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-63b5-7df9-be3c-6e5accb875a5" xlink:to="loc_tln_CommodityContractsUnrealizedGainLossMember_019e69cb-63b5-7767-92b8-d2b13b87522a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e69cb-63b5-714c-bf6a-ed3bde6b4db2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_Revenues_019e69cb-63b5-714c-bf6a-ed3bde6b4db2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingExpenseFuelUsedAndPurchasedPower_019e69cb-63b5-717a-9163-c3f4eb10b221" xlink:href="tln-20260630.xsd#tln_OperatingExpenseFuelUsedAndPurchasedPower"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_tln_OperatingExpenseFuelUsedAndPurchasedPower_019e69cb-63b5-717a-9163-c3f4eb10b221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfNuclearFuelLease_019e69cb-63b5-789c-bb20-0b69d3f8dfc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfNuclearFuelLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_AmortizationOfNuclearFuelLease_019e69cb-63b5-789c-bb20-0b69d3f8dfc2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_UnrealizedGainLossOnCommodityContractsEnergyExpenses_019e69cb-63b5-7a9f-b71b-ec23910ef29f" xlink:href="tln-20260630.xsd#tln_UnrealizedGainLossOnCommodityContractsEnergyExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_tln_UnrealizedGainLossOnCommodityContractsEnergyExpenses_019e69cb-63b5-7a9f-b71b-ec23910ef29f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnergyExpenses_019e69cb-63b5-7555-9a9f-cccc55c708f4" xlink:href="tln-20260630.xsd#tln_EnergyExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_tln_EnergyExpenses_019e69cb-63b5-7555-9a9f-cccc55c708f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019e69cb-63b5-76b7-b9c9-12d6e1304841" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019e69cb-63b5-76b7-b9c9-12d6e1304841" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperationMaintenanceAndDevelopmentExpense_019e69cb-63b5-7649-951b-a6b56ed407ff" xlink:href="tln-20260630.xsd#tln_OperationMaintenanceAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019e69cb-63b5-76b7-b9c9-12d6e1304841" xlink:to="loc_tln_OperationMaintenanceAndDevelopmentExpense_019e69cb-63b5-7649-951b-a6b56ed407ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019e69cb-63b5-70af-af55-7816eb3dde3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019e69cb-63b5-76b7-b9c9-12d6e1304841" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019e69cb-63b5-70af-af55-7816eb3dde3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019e69cb-63b5-7957-b7fb-a9267095334f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019e69cb-63b5-76b7-b9c9-12d6e1304841" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019e69cb-63b5-7957-b7fb-a9267095334f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_019e69cb-63b5-7e0a-870d-de87fe44d481" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019e69cb-63b5-76b7-b9c9-12d6e1304841" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_019e69cb-63b5-7e0a-870d-de87fe44d481" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e69cb-63b5-79fc-8b68-ff4871cbd70b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_OperatingIncomeLoss_019e69cb-63b5-79fc-8b68-ff4871cbd70b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_019e69cb-63b5-7b7c-95d0-6699e5bfbfb9" xlink:href="tln-20260630.xsd#tln_GainLossOnNuclearDecommissioningTrustFundsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_019e69cb-63b5-7b7c-95d0-6699e5bfbfb9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_019e69cb-63b5-75bd-9e83-8c3df9b4666b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_InterestAndDebtExpense_019e69cb-63b5-75bd-9e83-8c3df9b4666b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019e69cb-63b5-7ce1-84fe-5e34858f6c64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019e69cb-63b5-7ce1-84fe-5e34858f6c64" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e69cb-63b5-7ce6-b62d-fbd2998dec47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e69cb-63b5-7ce6-b62d-fbd2998dec47" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e69cb-63b5-7d44-b0ae-500fd4501c56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e69cb-63b5-7d44-b0ae-500fd4501c56" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e69cb-63b5-7cb7-9e65-05a80b29376a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_ProfitLoss_019e69cb-63b5-7cb7-9e65-05a80b29376a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_019e69cb-63b5-78ac-a2b6-00170bbfbceb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_019e69cb-63b5-78ac-a2b6-00170bbfbceb" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e69cb-63b5-7708-9a9b-ad4ccbd56b19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e69cb-63b5-78ac-a2b6-00170bbfbceb" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e69cb-63b5-7708-9a9b-ad4ccbd56b19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e69cb-63b5-7e67-8465-b78f4a845ab3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e69cb-63b5-78ac-a2b6-00170bbfbceb" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e69cb-63b5-7e67-8465-b78f4a845ab3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e69cb-63b5-78cf-bb4e-cb6b82885576" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e69cb-63b5-78ac-a2b6-00170bbfbceb" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e69cb-63b5-78cf-bb4e-cb6b82885576" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e69cb-63b5-7e05-beb6-6a74ade15461" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e69cb-63b5-78ac-a2b6-00170bbfbceb" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e69cb-63b5-7e05-beb6-6a74ade15461" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fcd43-07a8-7317-84e0-4839cfae265d" 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_StatementLineItems_019e69cb-63b5-720d-844f-0f6bcb4bfc0c" xlink:to="loc_us-gaap_NetIncomeLoss_019fcd43-07a8-7317-84e0-4839cfae265d" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CondensedConsolidatedStatementsOfEquityUnaudited" xlink:type="simple" xlink:href="tln-20260630.xsd#CondensedConsolidatedStatementsOfEquityUnaudited"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CondensedConsolidatedStatementsOfEquityUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e69cb-647d-7c57-a6b7-11fd9d447136" 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_019e69cb-647d-7b10-a5cc-65e314300bbe" 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_019e69cb-647d-7c57-a6b7-11fd9d447136" xlink:to="loc_us-gaap_StatementTable_019e69cb-647d-7b10-a5cc-65e314300bbe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f7e79-6d06-7049-974e-5e6730e63033" 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_019e69cb-647d-7b10-a5cc-65e314300bbe" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f7e79-6d06-7049-974e-5e6730e63033" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f7e79-6d06-7049-974e-5e6730e63033_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_019f7e79-6d06-7049-974e-5e6730e63033" xlink:to="loc_us-gaap_EquityComponentDomain_019f7e79-6d06-7049-974e-5e6730e63033_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f7e79-6d06-7b0e-91ec-20567d7470a6" 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_019f7e79-6d06-7049-974e-5e6730e63033" xlink:to="loc_us-gaap_EquityComponentDomain_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f7e79-6d06-7098-8cba-d07353a1f7c7" 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_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:to="loc_us-gaap_CommonStockMember_019f7e79-6d06-7098-8cba-d07353a1f7c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019f7e79-6d06-7cc3-a0cb-2331a4621bdd" 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_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019f7e79-6d06-7cc3-a0cb-2331a4621bdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019f7e79-6d06-7d55-840c-7e35b5a2cd8e" 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_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:to="loc_us-gaap_RetainedEarningsMember_019f7e79-6d06-7d55-840c-7e35b5a2cd8e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f7e79-6d06-77c3-9efe-bb740e0ef607" 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_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f7e79-6d06-77c3-9efe-bb740e0ef607" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019f7e79-6d06-74b7-a064-170b49e1a0cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019f7e79-6d06-74b7-a064-170b49e1a0cb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019f7e79-6d06-75dd-adb4-558eb1cbdd9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f7e79-6d06-7b0e-91ec-20567d7470a6" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019f7e79-6d06-75dd-adb4-558eb1cbdd9b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" 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_019e69cb-647d-7c57-a6b7-11fd9d447136" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e69cb-647d-7bd7-b650-51ee52c97169" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019e69cb-647d-7bd7-b650-51ee52c97169" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-647d-7827-9241-e5b4f2d20734" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-647d-7827-9241-e5b4f2d20734" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019f7e79-6d06-7ece-a985-62baac11feff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_ProfitLoss_019f7e79-6d06-7ece-a985-62baac11feff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f7e79-6d06-76d9-9588-a7581b61b259" 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_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f7e79-6d06-76d9-9588-a7581b61b259" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_019f7e79-6d06-75ce-838b-2eec9c9e1f31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_019f7e79-6d06-75ce-838b-2eec9c9e1f31" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f7e79-6d06-7e8b-9a05-6617b4ff7def" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f7e79-6d06-7e8b-9a05-6617b4ff7def" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_019f7e79-6d06-7a72-9bde-d872ec84faf4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockRetiredCostMethodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_019f7e79-6d06-7a72-9bde-d872ec84faf4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_019f7e79-6d06-7327-9d90-7fe56357f86f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_019f7e79-6d06-7327-9d90-7fe56357f86f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_019f7e7e-7ba4-7474-ba60-54947a46c1b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_019f7e7e-7ba4-7474-ba60-54947a46c1b1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestPeriodIncreaseDecrease_019f7e79-6d06-7adc-afe4-39ed33843c6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterestPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_MinorityInterestPeriodIncreaseDecrease_019f7e79-6d06-7adc-afe4-39ed33843c6d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansAndShareBasedPaymentArrangement_019f7e79-6d06-7def-9112-551287f47a60" xlink:href="tln-20260630.xsd#tln_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansAndShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_tln_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansAndShareBasedPaymentArrangement_019f7e79-6d06-7def-9112-551287f47a60" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f7e79-6d06-7bce-b05d-c59899bb0061" 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_019e69cb-647d-7576-b8e7-8a28eefa348d" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f7e79-6d06-7bce-b05d-c59899bb0061" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e69cb-647d-70a3-9d94-efe4b50c9755" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-647d-7e73-90e0-989eb7ccd0b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e69cb-647d-738e-9786-3f6b6c70edf0" 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_019e69cb-647d-7c60-b809-28af3bc424d3" 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_019e69cb-647d-738e-9786-3f6b6c70edf0" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e69cb-647d-7c60-b809-28af3bc424d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e69cb-647d-7041-91bc-176747783360" 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_019e69cb-647d-7c60-b809-28af3bc424d3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e69cb-647d-7041-91bc-176747783360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7041-91bc-176747783360_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_019e69cb-647d-7041-91bc-176747783360" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7041-91bc-176747783360_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-72d9-ba60-7ec0e1bd6c42" 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_019e69cb-647d-7041-91bc-176747783360" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-72d9-ba60-7ec0e1bd6c42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_019e69cb-647d-7532-9666-4a7de6947259" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-72d9-ba60-7ec0e1bd6c42" xlink:to="loc_us-gaap_NuclearFuelMember_019e69cb-647d-7532-9666-4a7de6947259" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGenerationCapacity_019e69cb-647d-71b5-a230-0c771191c416" xlink:href="tln-20260630.xsd#tln_PowerGenerationCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e69cb-647d-738e-9786-3f6b6c70edf0" xlink:to="loc_tln_PowerGenerationCapacity_019e69cb-647d-71b5-a230-0c771191c416" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofNetNotionalVolumesofOpenCommodityDerivativesandInterestRateDerivativesDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofNetNotionalVolumesofOpenCommodityDerivativesandInterestRateDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofNetNotionalVolumesofOpenCommodityDerivativesandInterestRateDerivativesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e69cb-647d-761d-872b-31d3a66057af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e69cb-647d-77c2-b608-b749a7cbf837" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-761d-872b-31d3a66057af" xlink:to="loc_us-gaap_DerivativeTable_019e69cb-647d-77c2-b608-b749a7cbf837" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-729e-929d-cb5411facaa1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e69cb-647d-77c2-b608-b749a7cbf837" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-729e-929d-cb5411facaa1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-729e-929d-cb5411facaa1_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_019e69cb-647d-729e-929d-cb5411facaa1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-729e-929d-cb5411facaa1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7ff3-bf9d-c0da92089655" 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_019e69cb-647d-729e-929d-cb5411facaa1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7ff3-bf9d-c0da92089655" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e69cb-647d-79e8-8e8e-ecf089bbcf0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7ff3-bf9d-c0da92089655" xlink:to="loc_us-gaap_CommodityContractMember_019e69cb-647d-79e8-8e8e-ecf089bbcf0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e69cb-647d-7d11-b0e3-6dde6c23e203" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7ff3-bf9d-c0da92089655" xlink:to="loc_us-gaap_InterestRateContractMember_019e69cb-647d-7d11-b0e3-6dde6c23e203" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_019e69cb-647d-7205-876a-ca8e6c7f6b3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e69cb-647d-77c2-b608-b749a7cbf837" xlink:to="loc_us-gaap_PositionAxis_019e69cb-647d-7205-876a-ca8e6c7f6b3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_019e69cb-647d-7205-876a-ca8e6c7f6b3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_019e69cb-647d-7205-876a-ca8e6c7f6b3c" xlink:to="loc_us-gaap_PositionDomain_019e69cb-647d-7205-876a-ca8e6c7f6b3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_019e69cb-647d-7600-99f4-510896b89c27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_019e69cb-647d-7205-876a-ca8e6c7f6b3c" xlink:to="loc_us-gaap_PositionDomain_019e69cb-647d-7600-99f4-510896b89c27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_019e69cb-647d-7cd9-a20b-64e46cf5d6d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_019e69cb-647d-7600-99f4-510896b89c27" xlink:to="loc_us-gaap_ShortMember_019e69cb-647d-7cd9-a20b-64e46cf5d6d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_019e69cb-647d-7ccf-975e-559ae866bbf8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_019e69cb-647d-7600-99f4-510896b89c27" xlink:to="loc_us-gaap_LongMember_019e69cb-647d-7ccf-975e-559ae866bbf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_019e69cb-647d-7b24-89e3-017f3f38733b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-761d-872b-31d3a66057af" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_019e69cb-647d-7b24-89e3-017f3f38733b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_019e69cb-647d-7415-ac21-cdae11d08fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountMass"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-761d-872b-31d3a66057af" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_019e69cb-647d-7415-ac21-cdae11d08fb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e69cb-647d-7cc0-a733-3bdff990fd55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-761d-872b-31d3a66057af" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e69cb-647d-7cc0-a733-3bdff990fd55" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e69cb-647d-791b-ae14-75bf54786af4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e69cb-647d-7d9a-a738-2827f020016f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-791b-ae14-75bf54786af4" xlink:to="loc_us-gaap_DerivativeTable_019e69cb-647d-7d9a-a738-2827f020016f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e69cb-647d-7384-a6a4-0cb4351b0927" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e69cb-647d-7d9a-a738-2827f020016f" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e69cb-647d-7384-a6a4-0cb4351b0927" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e69cb-647d-7384-a6a4-0cb4351b0927_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_019e69cb-647d-7384-a6a4-0cb4351b0927" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e69cb-647d-7384-a6a4-0cb4351b0927_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e69cb-647d-71b9-92fe-d923184ab858" 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_019e69cb-647d-7384-a6a4-0cb4351b0927" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e69cb-647d-71b9-92fe-d923184ab858" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TotalNetCreditExposureMember_019e69cb-647d-7be8-9869-b65752b27847" xlink:href="tln-20260630.xsd#tln_TotalNetCreditExposureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e69cb-647d-71b9-92fe-d923184ab858" xlink:to="loc_tln_TotalNetCreditExposureMember_019e69cb-647d-7be8-9869-b65752b27847" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019e69cb-647d-79ee-952e-eb6e27b9f7d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e69cb-647d-7d9a-a738-2827f020016f" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019e69cb-647d-79ee-952e-eb6e27b9f7d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019e69cb-647d-79ee-952e-eb6e27b9f7d5_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_019e69cb-647d-79ee-952e-eb6e27b9f7d5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019e69cb-647d-79ee-952e-eb6e27b9f7d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019e69cb-647d-7c3f-879a-6b84142d9bf8" 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_019e69cb-647d-79ee-952e-eb6e27b9f7d5" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019e69cb-647d-7c3f-879a-6b84142d9bf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditConcentrationRiskMember_019e69cb-647d-74ee-b3c4-0f2e85fbd219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019e69cb-647d-7c3f-879a-6b84142d9bf8" xlink:to="loc_us-gaap_CreditConcentrationRiskMember_019e69cb-647d-74ee-b3c4-0f2e85fbd219" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_019e69cb-647d-75e5-8f27-0f8bb30880cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e69cb-647d-7d9a-a738-2827f020016f" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_019e69cb-647d-75e5-8f27-0f8bb30880cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_019e69cb-647d-75e5-8f27-0f8bb30880cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_019e69cb-647d-75e5-8f27-0f8bb30880cf" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_019e69cb-647d-75e5-8f27-0f8bb30880cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_019e69cb-647d-72f9-b524-f8b413bf5e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_019e69cb-647d-75e5-8f27-0f8bb30880cf" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_019e69cb-647d-72f9-b524-f8b413bf5e9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TenLargestSingleNetCreditExposuresMember_019e69cb-647d-7e27-9d05-29f5d60a197d" xlink:href="tln-20260630.xsd#tln_TenLargestSingleNetCreditExposuresMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_019e69cb-647d-72f9-b524-f8b413bf5e9f" xlink:to="loc_tln_TenLargestSingleNetCreditExposuresMember_019e69cb-647d-7e27-9d05-29f5d60a197d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditDerivativeMaximumExposureUndiscounted_019e69cb-647d-79a2-b5f2-577118829dfb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditDerivativeMaximumExposureUndiscounted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-791b-ae14-75bf54786af4" xlink:to="loc_us-gaap_CreditDerivativeMaximumExposureUndiscounted_019e69cb-647d-79a2-b5f2-577118829dfb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CreditDerivativeMaximumExposureUndiscountedNet_019e69cb-647d-70b5-9768-de547fd0e9d2" xlink:href="tln-20260630.xsd#tln_CreditDerivativeMaximumExposureUndiscountedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-791b-ae14-75bf54786af4" xlink:to="loc_tln_CreditDerivativeMaximumExposureUndiscountedNet_019e69cb-647d-70b5-9768-de547fd0e9d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019e69cb-647d-7401-a6bd-d59eef0bbc2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-791b-ae14-75bf54786af4" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019e69cb-647d-7401-a6bd-d59eef0bbc2d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofBalanceSheetsPresentationDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofBalanceSheetsPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofBalanceSheetsPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e69cb-647d-7b15-9567-82bf42974db8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e69cb-647d-7062-9d59-da9e1494afe4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-7b15-9567-82bf42974db8" xlink:to="loc_us-gaap_DerivativeTable_019e69cb-647d-7062-9d59-da9e1494afe4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-771e-a6b1-cdf673e6baa6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e69cb-647d-7062-9d59-da9e1494afe4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-771e-a6b1-cdf673e6baa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-771e-a6b1-cdf673e6baa6_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_019e69cb-647d-771e-a6b1-cdf673e6baa6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-771e-a6b1-cdf673e6baa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-77ef-bcbe-b7710574becb" 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_019e69cb-647d-771e-a6b1-cdf673e6baa6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-77ef-bcbe-b7710574becb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e69cb-647d-73b7-9c7b-1302334fff43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-77ef-bcbe-b7710574becb" xlink:to="loc_us-gaap_CommodityContractMember_019e69cb-647d-73b7-9c7b-1302334fff43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e69cb-647d-78d5-98d5-91cc476cd334" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-77ef-bcbe-b7710574becb" xlink:to="loc_us-gaap_InterestRateContractMember_019e69cb-647d-78d5-98d5-91cc476cd334" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_019e69cb-647d-71eb-b552-22c4d48d2480" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-7b15-9567-82bf42974db8" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_019e69cb-647d-71eb-b552-22c4d48d2480" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_019e69cb-647d-79b7-a779-20d4c936d8bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-7b15-9567-82bf42974db8" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_019e69cb-647d-79b7-a779-20d4c936d8bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsNoncurrent_019e69cb-647d-711c-997d-7e065de45e9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-7b15-9567-82bf42974db8" xlink:to="loc_us-gaap_DerivativeAssetsNoncurrent_019e69cb-647d-711c-997d-7e065de45e9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019e69cb-647d-77ab-8421-4036f3e5fda0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e69cb-647d-7b15-9567-82bf42974db8" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019e69cb-647d-77ab-8421-4036f3e5fda0" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofStatementsofOperationsPresentationDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofStatementsofOperationsPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofStatementsofOperationsPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e69cb-647d-71e5-9478-3cb5c93ec842" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e69cb-647d-71e5-9478-3cb5c93ec842" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-7cd8-82f1-10dbcac71179" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-7cd8-82f1-10dbcac71179" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7cd8-82f1-10dbcac71179_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_019e69cb-647d-7cd8-82f1-10dbcac71179" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7cd8-82f1-10dbcac71179_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7457-8ca5-f28e401b095f" 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_019e69cb-647d-7cd8-82f1-10dbcac71179" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7457-8ca5-f28e401b095f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e69cb-647d-7590-82cc-af378dd63358" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7457-8ca5-f28e401b095f" xlink:to="loc_us-gaap_InterestRateContractMember_019e69cb-647d-7590-82cc-af378dd63358" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfCommodityContracts_019e69cb-647d-7c2f-892e-a62e6d17650b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_GainLossOnSaleOfCommodityContracts_019e69cb-647d-7c2f-892e-a62e6d17650b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_019e69cb-647d-7fc4-b834-80578224bacd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_019e69cb-647d-7fc4-b834-80578224bacd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e69cb-647d-7a9e-a0b7-bc9bbf0d70ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e69cb-647d-7a9e-a0b7-bc9bbf0d70ce" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofStatementsofOperationsPresentationDetails_1" xlink:type="simple" xlink:href="tln-20260630.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofStatementsofOperationsPresentationDetails_1"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofStatementsofOperationsPresentationDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-7cd8-82f1-10dbcac71179" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e69cb-647d-751f-8a50-14b26ae37ca6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-7cd8-82f1-10dbcac71179" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7cd8-82f1-10dbcac71179_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_019e69cb-647d-7cd8-82f1-10dbcac71179" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7cd8-82f1-10dbcac71179_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7457-8ca5-f28e401b095f" 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_019e69cb-647d-7cd8-82f1-10dbcac71179" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7457-8ca5-f28e401b095f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e69cb-647d-7590-82cc-af378dd63358" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7457-8ca5-f28e401b095f" xlink:to="loc_us-gaap_InterestRateContractMember_019e69cb-647d-7590-82cc-af378dd63358" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfCommodityContracts_019e69cb-647d-7c2f-892e-a62e6d17650b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_GainLossOnSaleOfCommodityContracts_019e69cb-647d-7c2f-892e-a62e6d17650b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_019e69cb-647d-7fc4-b834-80578224bacd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_019e69cb-647d-7fc4-b834-80578224bacd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e69cb-647d-7a9e-a0b7-bc9bbf0d70ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e69cb-647d-7adb-8d27-11c294583ca8" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e69cb-647d-7a9e-a0b7-bc9bbf0d70ce" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RevenueScheduleofComponentsofOperatingRevenuesDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#RevenueScheduleofComponentsofOperatingRevenuesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RevenueScheduleofComponentsofOperatingRevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e69cb-647d-7199-9bc1-d5c00310430a" 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_019e69cb-647d-7141-afd4-58418155dadd" 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_019e69cb-647d-7199-9bc1-d5c00310430a" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e69cb-647d-7141-afd4-58418155dadd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e69cb-647d-700d-a61d-b6eecaaa43a8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e69cb-647d-7141-afd4-58418155dadd" xlink:to="loc_srt_ProductOrServiceAxis_019e69cb-647d-700d-a61d-b6eecaaa43a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-647d-700d-a61d-b6eecaaa43a8_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-647d-700d-a61d-b6eecaaa43a8" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-647d-700d-a61d-b6eecaaa43a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-647d-77d4-8e00-04f1b818388b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-647d-700d-a61d-b6eecaaa43a8" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-647d-77d4-8e00-04f1b818388b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ElectricitySalesAndAncillaryServicesMember_019e69cb-647d-7b93-b036-14956d7f8aa6" xlink:href="tln-20260630.xsd#tln_ElectricitySalesAndAncillaryServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-77d4-8e00-04f1b818388b" xlink:to="loc_tln_ElectricitySalesAndAncillaryServicesMember_019e69cb-647d-7b93-b036-14956d7f8aa6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenueCapacityMember_019e69cb-647d-7976-a430-620eca5d2fd5" xlink:href="tln-20260630.xsd#tln_OperatingRevenueCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-77d4-8e00-04f1b818388b" xlink:to="loc_tln_OperatingRevenueCapacityMember_019e69cb-647d-7976-a430-620eca5d2fd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PhysicalElectricitySalesBilateralContractsOtherMember_019e69cb-647d-7338-be9a-9a702559f25e" xlink:href="tln-20260630.xsd#tln_PhysicalElectricitySalesBilateralContractsOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-77d4-8e00-04f1b818388b" xlink:to="loc_tln_PhysicalElectricitySalesBilateralContractsOtherMember_019e69cb-647d-7338-be9a-9a702559f25e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e69cb-647d-7489-bd61-8758364612f3" 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_019e69cb-647d-7199-9bc1-d5c00310430a" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e69cb-647d-7489-bd61-8758364612f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e69cb-647d-7296-ad05-9157490c53e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e69cb-647d-7199-9bc1-d5c00310430a" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e69cb-647d-7296-ad05-9157490c53e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome_019e69cb-647d-71b3-aa24-6978b08f5ac2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e69cb-647d-7199-9bc1-d5c00310430a" xlink:to="loc_us-gaap_OtherIncome_019e69cb-647d-71b3-aa24-6978b08f5ac2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e69cb-647d-71fd-a816-1b703a5953ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e69cb-647d-7199-9bc1-d5c00310430a" xlink:to="loc_us-gaap_Revenues_019e69cb-647d-71fd-a816-1b703a5953ef" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#RevenueScheduleofFuturePerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019e69cb-647d-7391-b9d0-9e0a975db56d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019e69cb-647d-7391-b9d0-9e0a975db56d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:to="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-647d-736b-a5d3-c9940f631b05_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-647d-736b-a5d3-c9940f631b05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ExpectedCapacityRevenueMember_019fad17-6be2-7a69-8477-183109322db5" xlink:href="tln-20260630.xsd#tln_ExpectedCapacityRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:to="loc_tln_ExpectedCapacityRevenueMember_019fad17-6be2-7a69-8477-183109322db5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityRevenue20282029PJMBRAMember_019f5bcc-46f3-7ae5-a7b6-7406c5f51630" xlink:href="tln-20260630.xsd#tln_CapacityRevenue20282029PJMBRAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:to="loc_tln_CapacityRevenue20282029PJMBRAMember_019f5bcc-46f3-7ae5-a7b6-7406c5f51630" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f881b-d940-767b-b176-19e84e9ed24e" 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_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f881b-d940-767b-b176-19e84e9ed24e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-767b-b176-19e84e9ed24e_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_019f881b-d940-767b-b176-19e84e9ed24e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-767b-b176-19e84e9ed24e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-7a06-a281-19a80eed91d9" 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_019f881b-d940-767b-b176-19e84e9ed24e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-7a06-a281-19a80eed91d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f881b-d940-7c01-98f8-82fd6351511a" 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_019f881b-d940-7a06-a281-19a80eed91d9" xlink:to="loc_us-gaap_SubsequentEventMember_019f881b-d940-7c01-98f8-82fd6351511a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019e69cb-647d-75d2-9f42-9f2cf0fa099c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019e69cb-647d-75d2-9f42-9f2cf0fa099c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e69cb-647d-7a80-8991-b47bdc46c7cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e69cb-647d-7a80-8991-b47bdc46c7cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityAuctionMegawattsCleared_019f881b-ee2d-756d-8b79-5ab397dbf0e5" xlink:href="tln-20260630.xsd#tln_CapacityAuctionMegawattsCleared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_tln_CapacityAuctionMegawattsCleared_019f881b-ee2d-756d-8b79-5ab397dbf0e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityAuctionClearingPricePerMegawattPerDay_019f881b-d940-7930-a793-96e428ed1798" xlink:href="tln-20260630.xsd#tln_CapacityAuctionClearingPricePerMegawattPerDay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_tln_CapacityAuctionClearingPricePerMegawattPerDay_019f881b-d940-7930-a793-96e428ed1798" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails_1" xlink:type="simple" xlink:href="tln-20260630.xsd#RevenueScheduleofFuturePerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:to="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-647d-736b-a5d3-c9940f631b05_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-647d-736b-a5d3-c9940f631b05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e69cb-647d-736b-a5d3-c9940f631b05" xlink:to="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ExpectedCapacityRevenueMember_019fad17-6be2-7a69-8477-183109322db5" xlink:href="tln-20260630.xsd#tln_ExpectedCapacityRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:to="loc_tln_ExpectedCapacityRevenueMember_019fad17-6be2-7a69-8477-183109322db5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityRevenue20282029PJMBRAMember_019f5bcc-46f3-7ae5-a7b6-7406c5f51630" xlink:href="tln-20260630.xsd#tln_CapacityRevenue20282029PJMBRAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e69cb-647d-7944-835d-71bd1bc94fa8" xlink:to="loc_tln_CapacityRevenue20282029PJMBRAMember_019f5bcc-46f3-7ae5-a7b6-7406c5f51630" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019f881b-d940-767b-b176-19e84e9ed24e" 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_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e69cb-647d-7549-8c7b-9856e2fa9fe0" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019f881b-d940-767b-b176-19e84e9ed24e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-767b-b176-19e84e9ed24e_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_019f881b-d940-767b-b176-19e84e9ed24e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-767b-b176-19e84e9ed24e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-7a06-a281-19a80eed91d9" 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_019f881b-d940-767b-b176-19e84e9ed24e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019f881b-d940-7a06-a281-19a80eed91d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019f881b-d940-7c01-98f8-82fd6351511a" 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_019f881b-d940-7a06-a281-19a80eed91d9" xlink:to="loc_us-gaap_SubsequentEventMember_019f881b-d940-7c01-98f8-82fd6351511a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019e69cb-647d-75d2-9f42-9f2cf0fa099c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019e69cb-647d-75d2-9f42-9f2cf0fa099c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e69cb-647d-7a80-8991-b47bdc46c7cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e69cb-647d-7a80-8991-b47bdc46c7cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityAuctionMegawattsCleared_019f881b-ee2d-756d-8b79-5ab397dbf0e5" xlink:href="tln-20260630.xsd#tln_CapacityAuctionMegawattsCleared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_tln_CapacityAuctionMegawattsCleared_019f881b-ee2d-756d-8b79-5ab397dbf0e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityAuctionClearingPricePerMegawattPerDay_019f881b-d940-7930-a793-96e428ed1798" xlink:href="tln-20260630.xsd#tln_CapacityAuctionClearingPricePerMegawattPerDay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e69cb-647d-7738-836f-ba57008ca5ee" xlink:to="loc_tln_CapacityAuctionClearingPricePerMegawattPerDay_019f881b-d940-7930-a793-96e428ed1798" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofUnrealizedGainLossonNuclearDecommissioningTrustFundsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#NuclearDecommissioningTrustFundsScheduleofUnrealizedGainLossonNuclearDecommissioningTrustFundsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofUnrealizedGainLossonNuclearDecommissioningTrustFundsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_019e69cb-647d-74aa-bb40-c4a10e5ec5ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_019e69cb-647d-74aa-bb40-c4a10e5ec5ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_019e69cb-647d-74f4-b4ac-0b8c42c89fec" 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_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_019e69cb-647d-74aa-bb40-c4a10e5ec5ee" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_019e69cb-647d-74f4-b4ac-0b8c42c89fec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e69cb-647d-74f4-b4ac-0b8c42c89fec_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_019e69cb-647d-74f4-b4ac-0b8c42c89fec" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e69cb-647d-74f4-b4ac-0b8c42c89fec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e69cb-647d-795c-86d9-70a3ad335947" 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_019e69cb-647d-74f4-b4ac-0b8c42c89fec" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e69cb-647d-795c-86d9-70a3ad335947" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsMember_019e69cb-647d-759f-905f-7e1f64714fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e69cb-647d-795c-86d9-70a3ad335947" xlink:to="loc_us-gaap_CashEquivalentsMember_019e69cb-647d-759f-905f-7e1f64714fb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e69cb-647d-7c8d-9f38-721ce3ebe1a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e69cb-647d-7c8d-9f38-721ce3ebe1a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e69cb-647d-7a35-81d0-f70768d877d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e69cb-647d-7a35-81d0-f70768d877d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCost_019e69cb-647d-7a07-ba67-cc014b3b9aba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCost_019e69cb-647d-7a07-ba67-cc014b3b9aba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax_019e69cb-647d-775b-8927-e8ba0f945589" xlink:href="tln-20260630.xsd#tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax_019e69cb-647d-775b-8927-e8ba0f945589" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax_019e69cb-647d-7829-ab50-f91a154f240a" xlink:href="tln-20260630.xsd#tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax_019e69cb-647d-7829-ab50-f91a154f240a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_019e69cb-647d-7c2c-9b6f-c8cd55c05a8c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_019e69cb-647d-7c2c-9b6f-c8cd55c05a8c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019e69cb-647d-774c-9756-df701f71fac0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019e69cb-647d-774c-9756-df701f71fac0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019e69cb-647d-77a1-91ea-257d4ef46923" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019e69cb-647d-77a1-91ea-257d4ef46923" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019e69cb-647d-7085-9d9c-46686e51b9e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019e69cb-647d-7085-9d9c-46686e51b9e4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019e69cb-647d-70fe-bf01-1d6defee47e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019e69cb-647d-70fe-bf01-1d6defee47e3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReceivablesPayablesNetAmortizedCost_019e69cb-647d-7efc-a3e8-4402a575b78e" xlink:href="tln-20260630.xsd#tln_ReceivablesPayablesNetAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_ReceivablesPayablesNetAmortizedCost_019e69cb-647d-7efc-a3e8-4402a575b78e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReceivablesPayablesNetFairValue_019e69cb-647d-7687-8b41-5b22eee5e90f" xlink:href="tln-20260630.xsd#tln_ReceivablesPayablesNetFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_ReceivablesPayablesNetFairValue_019e69cb-647d-7687-8b41-5b22eee5e90f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DecommissioningFundInvestmentsAmortizedCost_019e69cb-647d-7d1a-9642-f21abfdbcadf" xlink:href="tln-20260630.xsd#tln_DecommissioningFundInvestmentsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_DecommissioningFundInvestmentsAmortizedCost_019e69cb-647d-7d1a-9642-f21abfdbcadf" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedGainBeforeTax_019e69cb-647d-75ad-a490-17f5fee6d075" xlink:href="tln-20260630.xsd#tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedGainBeforeTax_019e69cb-647d-75ad-a490-17f5fee6d075" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedLossBeforeTax_019e69cb-647d-7559-b22d-23fc95c9d311" xlink:href="tln-20260630.xsd#tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedLossBeforeTax_019e69cb-647d-7559-b22d-23fc95c9d311" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_019e69cb-647d-7e61-99a8-64e3e3bfec76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-72a6-aa02-297afb49b719" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_019e69cb-647d-7e61-99a8-64e3e3bfec76" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofAvailableforSaleDebtSecuritiesWithUnrealizedLossesDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#NuclearDecommissioningTrustFundsScheduleofAvailableforSaleDebtSecuritiesWithUnrealizedLossesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofAvailableforSaleDebtSecuritiesWithUnrealizedLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-7441-bee0-0311fc770147" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_019e69cb-647d-75af-a64d-5ee91a79ef39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-7441-bee0-0311fc770147" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_019e69cb-647d-75af-a64d-5ee91a79ef39" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7351-880f-e723e82c822f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_019e69cb-647d-75af-a64d-5ee91a79ef39" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7351-880f-e723e82c822f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7351-880f-e723e82c822f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7351-880f-e723e82c822f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7351-880f-e723e82c822f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7aa1-ab9f-cccf7bcc5f2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7351-880f-e723e82c822f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7aa1-ab9f-cccf7bcc5f2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019e69cb-647d-7897-9486-1f7121a67375" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7aa1-ab9f-cccf7bcc5f2e" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019e69cb-647d-7897-9486-1f7121a67375" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_019e69cb-647d-709b-8ba6-b134ff30f02c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7aa1-ab9f-cccf7bcc5f2e" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_019e69cb-647d-709b-8ba6-b134ff30f02c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentDebtSecuritiesMember_019e69cb-647d-714d-92c1-1dcdbcdf017f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7aa1-ab9f-cccf7bcc5f2e" xlink:to="loc_us-gaap_USGovernmentDebtSecuritiesMember_019e69cb-647d-714d-92c1-1dcdbcdf017f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019e69cb-647d-7535-971b-75cad47bb828" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-7441-bee0-0311fc770147" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019e69cb-647d-7535-971b-75cad47bb828" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_019e69cb-647d-703c-9175-7ec6b0639583" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_019e69cb-647d-7441-bee0-0311fc770147" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_019e69cb-647d-703c-9175-7ec6b0639583" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e69cb-647d-718a-99f4-11a584f2c7d8" 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_019e69cb-647d-7eb1-85bb-1752d9416a51" 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_019e69cb-647d-718a-99f4-11a584f2c7d8" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e69cb-647d-7eb1-85bb-1752d9416a51" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e69cb-647d-7117-b60d-e4a686600abb" 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_019e69cb-647d-7eb1-85bb-1752d9416a51" xlink:to="loc_srt_RangeAxis_019e69cb-647d-7117-b60d-e4a686600abb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-647d-7117-b60d-e4a686600abb_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_019e69cb-647d-7117-b60d-e4a686600abb" xlink:to="loc_srt_RangeMember_019e69cb-647d-7117-b60d-e4a686600abb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-647d-70a7-9ae8-5b60edd32e84" 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_019e69cb-647d-7117-b60d-e4a686600abb" xlink:to="loc_srt_RangeMember_019e69cb-647d-70a7-9ae8-5b60edd32e84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e69cb-647d-7791-8910-eb0ae91b6ceb" 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_019e69cb-647d-70a7-9ae8-5b60edd32e84" xlink:to="loc_srt_MinimumMember_019e69cb-647d-7791-8910-eb0ae91b6ceb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e69cb-647d-7c62-8774-764039d1197d" 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_019e69cb-647d-70a7-9ae8-5b60edd32e84" xlink:to="loc_srt_MaximumMember_019e69cb-647d-7c62-8774-764039d1197d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e69cb-647d-78de-92a9-31ca5cc5a5f3" 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_019e69cb-647d-7eb1-85bb-1752d9416a51" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e69cb-647d-78de-92a9-31ca5cc5a5f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-78de-92a9-31ca5cc5a5f3_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_019e69cb-647d-78de-92a9-31ca5cc5a5f3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-78de-92a9-31ca5cc5a5f3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7dd7-b27a-1d2a78a411aa" 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_019e69cb-647d-78de-92a9-31ca5cc5a5f3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7dd7-b27a-1d2a78a411aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ElectricityGenerationMember_019e69cb-647d-75ea-9349-f2a877d9f8d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ElectricityGenerationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7dd7-b27a-1d2a78a411aa" xlink:to="loc_us-gaap_ElectricityGenerationMember_019e69cb-647d-75ea-9349-f2a877d9f8d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_019e69cb-647d-79c3-8ed7-cf943c675799" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7dd7-b27a-1d2a78a411aa" xlink:to="loc_us-gaap_NuclearFuelMember_019e69cb-647d-79c3-8ed7-cf943c675799" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_019e69cb-647d-73a6-9dd2-a3f1aaf5f142" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOtherTypesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7dd7-b27a-1d2a78a411aa" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_019e69cb-647d-73a6-9dd2-a3f1aaf5f142" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_019e69cb-647d-7803-8691-c05bda8e840e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7dd7-b27a-1d2a78a411aa" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_019e69cb-647d-7803-8691-c05bda8e840e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_019e69cb-647d-75e6-93ba-8d325a1da677" 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_019e69cb-647d-7dd7-b27a-1d2a78a411aa" xlink:to="loc_us-gaap_ConstructionInProgressMember_019e69cb-647d-75e6-93ba-8d325a1da677" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e69cb-647d-73b4-9cc5-82746fd960c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e69cb-647d-718a-99f4-11a584f2c7d8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e69cb-647d-73b4-9cc5-82746fd960c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019e69cb-647d-7a5f-b174-9754237705b2" 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_PropertyPlantAndEquipmentNetAbstract_019e69cb-647d-73b4-9cc5-82746fd960c6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019e69cb-647d-7a5f-b174-9754237705b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019e69cb-647d-7127-b0d5-6836c7cf86ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e69cb-647d-73b4-9cc5-82746fd960c6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019e69cb-647d-7127-b0d5-6836c7cf86ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e69cb-647d-7a3e-b075-7b1915f8d8d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e69cb-647d-73b4-9cc5-82746fd960c6" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e69cb-647d-7a3e-b075-7b1915f8d8d3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e69cb-647d-79ed-96b0-5348fd1dbf18" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_019e69cb-647d-73b4-9cc5-82746fd960c6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e69cb-647d-79ed-96b0-5348fd1dbf18" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AssetRetirementObligationsandAccruedEnvironmentalCostsScheduleofDisaggregationofAssetRetirementObligationsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AssetRetirementObligationsandAccruedEnvironmentalCostsScheduleofDisaggregationofAssetRetirementObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AssetRetirementObligationsandAccruedEnvironmentalCostsScheduleofDisaggregationofAssetRetirementObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tln_AssetRetirementObligationLineItems_019e69cb-647d-7666-b763-407cb745e22c" xlink:href="tln-20260630.xsd#tln_AssetRetirementObligationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AssetRetirementObligationTable_019e69cb-647d-7d47-b20f-bf41161fb1bc" xlink:href="tln-20260630.xsd#tln_AssetRetirementObligationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_tln_AssetRetirementObligationLineItems_019e69cb-647d-7666-b763-407cb745e22c" xlink:to="loc_tln_AssetRetirementObligationTable_019e69cb-647d-7d47-b20f-bf41161fb1bc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_019e69cb-647d-78f9-9973-466dc885311e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tln_AssetRetirementObligationTable_019e69cb-647d-7d47-b20f-bf41161fb1bc" xlink:to="loc_srt_EnergyAxis_019e69cb-647d-78f9-9973-466dc885311e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019e69cb-647d-78f9-9973-466dc885311e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_019e69cb-647d-78f9-9973-466dc885311e" xlink:to="loc_srt_EnergyDomain_019e69cb-647d-78f9-9973-466dc885311e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019e69cb-647d-73cf-9d17-1221060098d6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_019e69cb-647d-78f9-9973-466dc885311e" xlink:to="loc_srt_EnergyDomain_019e69cb-647d-73cf-9d17-1221060098d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_019e69cb-647d-78ce-93fd-7aebd8a9a386" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019e69cb-647d-73cf-9d17-1221060098d6" xlink:to="loc_us-gaap_NuclearFuelMember_019e69cb-647d-78ce-93fd-7aebd8a9a386" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NonNuclearFuelMember_019e69cb-647d-762a-828d-0bac0c59340e" xlink:href="tln-20260630.xsd#tln_NonNuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019e69cb-647d-73cf-9d17-1221060098d6" xlink:to="loc_tln_NonNuclearFuelMember_019e69cb-647d-762a-828d-0bac0c59340e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligation_019e69cb-647d-79ce-8f59-d2daa5dcfbb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_AssetRetirementObligationLineItems_019e69cb-647d-7666-b763-407cb745e22c" xlink:to="loc_us-gaap_AssetRetirementObligation_019e69cb-647d-79ce-8f59-d2daa5dcfbb3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesLegalMattersDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#CommitmentsandContingenciesLegalMattersDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesLegalMattersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019fad1d-d593-7236-b76e-8cccf63ca63c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019fad1d-d593-79ac-811c-dbdd80eaa57d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019fad1d-d593-7236-b76e-8cccf63ca63c" xlink:to="loc_us-gaap_OtherCommitmentsTable_019fad1d-d593-79ac-811c-dbdd80eaa57d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fad1d-d593-79b8-9ab7-0303d51856d4" 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_OtherCommitmentsTable_019fad1d-d593-79ac-811c-dbdd80eaa57d" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fad1d-d593-79b8-9ab7-0303d51856d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fad1d-d593-79b8-9ab7-0303d51856d4_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_019fad1d-d593-79b8-9ab7-0303d51856d4" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fad1d-d593-79b8-9ab7-0303d51856d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fad1d-d593-7bf8-bf73-82db2ba9a3b8" 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_019fad1d-d593-79b8-9ab7-0303d51856d4" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fad1d-d593-7bf8-bf73-82db2ba9a3b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fad1d-d593-76d8-b240-9a1e67f4ffe7" 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_019fad1d-d593-7bf8-bf73-82db2ba9a3b8" xlink:to="loc_us-gaap_SubsequentEventMember_019fad1d-d593-76d8-b240-9a1e67f4ffe7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019fad1e-7a2f-77e0-9b24-083987a6de58" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019fad1d-d593-79ac-811c-dbdd80eaa57d" xlink:to="loc_srt_LitigationCaseAxis_019fad1e-7a2f-77e0-9b24-083987a6de58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019fad1e-7a2f-77e0-9b24-083987a6de58_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019fad1e-7a2f-77e0-9b24-083987a6de58" xlink:to="loc_srt_LitigationCaseTypeDomain_019fad1e-7a2f-77e0-9b24-083987a6de58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019fad1e-7a2f-7968-8f94-78103c12c919" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019fad1e-7a2f-77e0-9b24-083987a6de58" xlink:to="loc_srt_LitigationCaseTypeDomain_019fad1e-7a2f-7968-8f94-78103c12c919" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SpentNuclearFuelMember_019fad1e-7a2f-7a66-a023-16afb49d2d28" xlink:href="tln-20260630.xsd#tln_SpentNuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019fad1e-7a2f-7968-8f94-78103c12c919" xlink:to="loc_tln_SpentNuclearFuelMember_019fad1e-7a2f-7a66-a023-16afb49d2d28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019fad1e-7a2f-7516-b073-76110178001c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019fad1d-d593-79ac-811c-dbdd80eaa57d" xlink:to="loc_us-gaap_LitigationStatusAxis_019fad1e-7a2f-7516-b073-76110178001c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019fad1e-7a2f-7516-b073-76110178001c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019fad1e-7a2f-7516-b073-76110178001c" xlink:to="loc_us-gaap_LitigationStatusDomain_019fad1e-7a2f-7516-b073-76110178001c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019fad1e-7a2f-7f5d-87dc-9f8f4b3fec4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019fad1e-7a2f-7516-b073-76110178001c" xlink:to="loc_us-gaap_LitigationStatusDomain_019fad1e-7a2f-7f5d-87dc-9f8f4b3fec4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettledLitigationMember_019fad1e-7a2f-780c-b98b-cfbdff97805b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SettledLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019fad1e-7a2f-7f5d-87dc-9f8f4b3fec4b" xlink:to="loc_us-gaap_SettledLitigationMember_019fad1e-7a2f-780c-b98b-cfbdff97805b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedFromOtherParty_019fad1e-7a2f-7bac-920a-cb0bad0806d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedFromOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019fad1d-d593-7236-b76e-8cccf63ca63c" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedFromOtherParty_019fad1e-7a2f-7bac-920a-cb0bad0806d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LossContingencyPercentageShareOfStorageCosts_019fad1d-d593-79a1-9afa-76a6e5213e2d" xlink:href="tln-20260630.xsd#tln_LossContingencyPercentageShareOfStorageCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019fad1d-d593-7236-b76e-8cccf63ca63c" xlink:to="loc_tln_LossContingencyPercentageShareOfStorageCosts_019fad1d-d593-79a1-9afa-76a6e5213e2d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesRegulatoryMattersDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#CommitmentsandContingenciesRegulatoryMattersDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesRegulatoryMattersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7fcb-a27b-921654985eb2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7fcb-a27b-921654985eb2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e69cb-647d-7141-bd9e-a57e3a387d98" 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_OtherCommitmentsTable_019e69cb-647d-7fcb-a27b-921654985eb2" xlink:to="loc_srt_RangeAxis_019e69cb-647d-7141-bd9e-a57e3a387d98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-647d-7141-bd9e-a57e3a387d98_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_019e69cb-647d-7141-bd9e-a57e3a387d98" xlink:to="loc_srt_RangeMember_019e69cb-647d-7141-bd9e-a57e3a387d98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-647d-71a8-9530-5e68e8cbe6bf" 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_019e69cb-647d-7141-bd9e-a57e3a387d98" xlink:to="loc_srt_RangeMember_019e69cb-647d-71a8-9530-5e68e8cbe6bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e69cb-647d-7c85-8969-207ce1efeb4a" 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_019e69cb-647d-71a8-9530-5e68e8cbe6bf" xlink:to="loc_srt_MinimumMember_019e69cb-647d-7c85-8969-207ce1efeb4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e69cb-647d-746d-83cc-f37c98ccc517" 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_019e69cb-647d-71a8-9530-5e68e8cbe6bf" xlink:to="loc_srt_MaximumMember_019e69cb-647d-746d-83cc-f37c98ccc517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e69cb-647d-7b24-899d-f7e888438209" 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_OtherCommitmentsTable_019e69cb-647d-7fcb-a27b-921654985eb2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e69cb-647d-7b24-899d-f7e888438209" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7b24-899d-f7e888438209_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_019e69cb-647d-7b24-899d-f7e888438209" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-7b24-899d-f7e888438209_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-79f8-a9a6-3bd41128d786" 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_019e69cb-647d-7b24-899d-f7e888438209" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-79f8-a9a6-3bd41128d786" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BrandonShoresMember_019e69cb-647d-7c54-ac11-80d4f95be21f" xlink:href="tln-20260630.xsd#tln_BrandonShoresMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-79f8-a9a6-3bd41128d786" xlink:to="loc_tln_BrandonShoresMember_019e69cb-647d-7c54-ac11-80d4f95be21f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_WagnerMember_019e69cb-647d-7541-b121-f27dd4fe9e5f" xlink:href="tln-20260630.xsd#tln_WagnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-79f8-a9a6-3bd41128d786" xlink:to="loc_tln_WagnerMember_019e69cb-647d-7541-b121-f27dd4fe9e5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PJMReliabilityBackstopProcurementMember_019faf07-f7e1-7004-99e5-fe3dd3ffe51f" xlink:href="tln-20260630.xsd#tln_PJMReliabilityBackstopProcurementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e69cb-647d-79f8-a9a6-3bd41128d786" xlink:to="loc_tln_PJMReliabilityBackstopProcurementMember_019faf07-f7e1-7004-99e5-fe3dd3ffe51f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fc850-ecc6-723d-8039-424398f0bde1" 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_OtherCommitmentsTable_019e69cb-647d-7fcb-a27b-921654985eb2" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fc850-ecc6-723d-8039-424398f0bde1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc850-ecc6-723d-8039-424398f0bde1_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_019fc850-ecc6-723d-8039-424398f0bde1" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc850-ecc6-723d-8039-424398f0bde1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fc850-ecc6-7623-8885-1970417c1fb6" 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_019fc850-ecc6-723d-8039-424398f0bde1" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fc850-ecc6-7623-8885-1970417c1fb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fc850-fce6-72c2-9645-bcbda54762c2" 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_019fc850-ecc6-7623-8885-1970417c1fb6" xlink:to="loc_us-gaap_SubsequentEventMember_019fc850-fce6-72c2-9645-bcbda54762c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_RequestedDelayDuration_019e69cb-647d-71c0-bcf1-630686e56c1c" xlink:href="tln-20260630.xsd#tln_RequestedDelayDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_RequestedDelayDuration_019e69cb-647d-71c0-bcf1-630686e56c1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfFERCFilings_019e69cb-647d-793a-b2a6-8f44bc1fe21a" xlink:href="tln-20260630.xsd#tln_NumberOfFERCFilings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_NumberOfFERCFilings_019e69cb-647d-793a-b2a6-8f44bc1fe21a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfDeliveryYears_019e69cb-647d-7337-aa96-0ea2818cc659" xlink:href="tln-20260630.xsd#tln_NumberOfDeliveryYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_NumberOfDeliveryYears_019e69cb-647d-7337-aa96-0ea2818cc659" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CollarOnCapacityPrice_019e69cb-647d-7549-aedb-4db25e6d126b" xlink:href="tln-20260630.xsd#tln_CollarOnCapacityPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_CollarOnCapacityPrice_019e69cb-647d-7549-aedb-4db25e6d126b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_FixedCostAnnualPayments_019e69cb-647d-7ff4-8d43-e146ebf045c4" xlink:href="tln-20260630.xsd#tln_FixedCostAnnualPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_FixedCostAnnualPayments_019e69cb-647d-7ff4-8d43-e146ebf045c4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_FixedCostPricePerMWPerDay_019e69cb-647d-7a7b-aa39-f514cc25a687" xlink:href="tln-20260630.xsd#tln_FixedCostPricePerMWPerDay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_FixedCostPricePerMWPerDay_019e69cb-647d-7a7b-aa39-f514cc25a687" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PerformanceHoldBackPerYear_019e69cb-647d-712f-a535-313613863d40" xlink:href="tln-20260630.xsd#tln_PerformanceHoldBackPerYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_PerformanceHoldBackPerYear_019e69cb-647d-712f-a535-313613863d40" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfStatesInPJM_019e69cb-647d-7836-b35c-3350211816b5" xlink:href="tln-20260630.xsd#tln_NumberOfStatesInPJM"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_NumberOfStatesInPJM_019e69cb-647d-7836-b35c-3350211816b5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReliabilityBackstopAuctionBaseloadCapacityContractTerm_019e69cb-647d-7854-aa3c-d8312c75fb3a" xlink:href="tln-20260630.xsd#tln_ReliabilityBackstopAuctionBaseloadCapacityContractTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_ReliabilityBackstopAuctionBaseloadCapacityContractTerm_019e69cb-647d-7854-aa3c-d8312c75fb3a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfBaseResidualAuctions_019e69cb-647d-74c0-95b1-8e137020b1ed" xlink:href="tln-20260630.xsd#tln_NumberOfBaseResidualAuctions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_NumberOfBaseResidualAuctions_019e69cb-647d-74c0-95b1-8e137020b1ed" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfDaysToRespond_019fb0c7-c178-7e98-a52f-7f568ec16411" xlink:href="tln-20260630.xsd#tln_NumberOfDaysToRespond"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_NumberOfDaysToRespond_019fb0c7-c178-7e98-a52f-7f568ec16411" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfDaysToSubmitInformationalReport_019faf09-0c1d-73a2-8d55-3c0068d1497d" xlink:href="tln-20260630.xsd#tln_NumberOfDaysToSubmitInformationalReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_NumberOfDaysToSubmitInformationalReport_019faf09-0c1d-73a2-8d55-3c0068d1497d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BaseResidualAuctionShortfallUtilizedForOneTimePayAsBid_019fc852-b55a-793f-9745-aa445df35c79" xlink:href="tln-20260630.xsd#tln_BaseResidualAuctionShortfallUtilizedForOneTimePayAsBid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_BaseResidualAuctionShortfallUtilizedForOneTimePayAsBid_019fc852-b55a-793f-9745-aa445df35c79" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CapacityContractTerm_019fc853-d1e5-7807-9a4b-44e28000af55" xlink:href="tln-20260630.xsd#tln_CapacityContractTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7dd1-bdfb-08175726d696" xlink:to="loc_tln_CapacityContractTerm_019fc853-d1e5-7807-9a4b-44e28000af55" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesEnvironmentalMattersDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#CommitmentsandContingenciesEnvironmentalMattersDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesEnvironmentalMattersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7c5e-afe0-64c56b24a076" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7ff6-9d80-3d5361305628" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7c5e-afe0-64c56b24a076" xlink:to="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7ff6-9d80-3d5361305628" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e69cb-647d-7203-a5ea-85b1df98e9d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7ff6-9d80-3d5361305628" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e69cb-647d-7203-a5ea-85b1df98e9d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-7203-a5ea-85b1df98e9d5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e69cb-647d-7203-a5ea-85b1df98e9d5" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-7203-a5ea-85b1df98e9d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-74ec-9229-ec3dc70131cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e69cb-647d-7203-a5ea-85b1df98e9d5" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-74ec-9229-ec3dc70131cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPAMATSRuleMember_019e69cb-647d-7c59-94cc-ee5d0b846c56" xlink:href="tln-20260630.xsd#tln_EnvironmentalMattersEPAMATSRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-74ec-9229-ec3dc70131cf" xlink:to="loc_tln_EnvironmentalMattersEPAMATSRuleMember_019e69cb-647d-7c59-94cc-ee5d0b846c56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPAGHGRuleMember_019e69cb-647d-7d18-a9f5-c0113d9a0ca0" xlink:href="tln-20260630.xsd#tln_EnvironmentalMattersEPAGHGRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-74ec-9229-ec3dc70131cf" xlink:to="loc_tln_EnvironmentalMattersEPAGHGRuleMember_019e69cb-647d-7d18-a9f5-c0113d9a0ca0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPAELGRuleMember_019e69cb-647d-7caf-a075-24611f60b308" xlink:href="tln-20260630.xsd#tln_EnvironmentalMattersEPAELGRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-74ec-9229-ec3dc70131cf" xlink:to="loc_tln_EnvironmentalMattersEPAELGRuleMember_019e69cb-647d-7caf-a075-24611f60b308" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPACCRRuleMember_019e69cb-647d-7e6e-ae02-5db57d29d904" xlink:href="tln-20260630.xsd#tln_EnvironmentalMattersEPACCRRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e69cb-647d-74ec-9229-ec3dc70131cf" xlink:to="loc_tln_EnvironmentalMattersEPACCRRuleMember_019e69cb-647d-7e6e-ae02-5db57d29d904" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LossContingencyNumberOfStates_019e69cb-647d-7247-ab1c-fc2edb4ce61b" xlink:href="tln-20260630.xsd#tln_LossContingencyNumberOfStates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7c5e-afe0-64c56b24a076" xlink:to="loc_tln_LossContingencyNumberOfStates_019e69cb-647d-7247-ab1c-fc2edb4ce61b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfStatesRepresentedByCoalitions_019e69cb-647d-7fdc-a349-a5f617da2bb6" xlink:href="tln-20260630.xsd#tln_NumberOfStatesRepresentedByCoalitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7c5e-afe0-64c56b24a076" xlink:to="loc_tln_NumberOfStatesRepresentedByCoalitions_019e69cb-647d-7fdc-a349-a5f617da2bb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LossContingencyNumberOfIndustryGroups_019e69cb-647d-7c14-a00a-d16f9a781e9c" xlink:href="tln-20260630.xsd#tln_LossContingencyNumberOfIndustryGroups"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7c5e-afe0-64c56b24a076" xlink:to="loc_tln_LossContingencyNumberOfIndustryGroups_019e69cb-647d-7c14-a00a-d16f9a781e9c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesGuaranteesandOtherAssurancesDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#CommitmentsandContingenciesGuaranteesandOtherAssurancesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesGuaranteesandOtherAssurancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7f06-aa6e-e31380a6117c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7c31-b1d8-29f262cddc75" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7f06-aa6e-e31380a6117c" xlink:to="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7c31-b1d8-29f262cddc75" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e69cb-647d-7fb5-8005-8f4b6cb87959" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7c31-b1d8-29f262cddc75" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e69cb-647d-7fb5-8005-8f4b6cb87959" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_019e69cb-647d-7fb5-8005-8f4b6cb87959_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e69cb-647d-7fb5-8005-8f4b6cb87959" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_019e69cb-647d-7fb5-8005-8f4b6cb87959_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_019e69cb-647d-7776-a46c-9592b3f55546" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e69cb-647d-7fb5-8005-8f4b6cb87959" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_019e69cb-647d-7776-a46c-9592b3f55546" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SuretyBondMember_019e69cb-647d-79ea-b540-2d82df659050" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SuretyBondMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_019e69cb-647d-7776-a46c-9592b3f55546" xlink:to="loc_us-gaap_SuretyBondMember_019e69cb-647d-79ea-b540-2d82df659050" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e69cb-647d-7229-a72e-494e2d3ade52" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019e69cb-647d-7c31-b1d8-29f262cddc75" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e69cb-647d-7229-a72e-494e2d3ade52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e69cb-647d-7229-a72e-494e2d3ade52_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e69cb-647d-7229-a72e-494e2d3ade52" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e69cb-647d-7229-a72e-494e2d3ade52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e69cb-647d-7ed1-b063-61f9ec39f2c7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e69cb-647d-7229-a72e-494e2d3ade52" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e69cb-647d-7ed1-b063-61f9ec39f2c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SubsidiariesMember_019e69cb-647d-7e2e-900e-ab3d6a12acc7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e69cb-647d-7ed1-b063-61f9ec39f2c7" xlink:to="loc_srt_SubsidiariesMember_019e69cb-647d-7e2e-900e-ab3d6a12acc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_019e69cb-647d-7586-aead-642036b301dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e69cb-647d-7f06-aa6e-e31380a6117c" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_019e69cb-647d-7586-aead-642036b301dd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#LongTermDebtandOtherCreditFacilitiesScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e69cb-647d-79e4-9e11-1ba119aebe1f" 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_019e69cb-647d-7685-a161-91462b17fe6c" 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_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_DebtInstrumentTable_019e69cb-647d-7685-a161-91462b17fe6c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e69cb-647d-7404-96ac-0919ca884224" 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_019e69cb-647d-7685-a161-91462b17fe6c" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e69cb-647d-7404-96ac-0919ca884224" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7404-96ac-0919ca884224_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_019e69cb-647d-7404-96ac-0919ca884224" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7404-96ac-0919ca884224_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" 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_019e69cb-647d-7404-96ac-0919ca884224" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB1FacilityMember_019e69cb-647d-7b0f-bac7-0f05797b174e" xlink:href="tln-20260630.xsd#tln_TLB1FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_TLB1FacilityMember_019e69cb-647d-7b0f-bac7-0f05797b174e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB2FacilityMember_019e69cb-647d-7b31-9e6c-39e151a51f66" xlink:href="tln-20260630.xsd#tln_TLB2FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_TLB2FacilityMember_019e69cb-647d-7b31-9e6c-39e151a51f66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB3FacilityMember_019e69cb-647d-7d94-bdf1-276d6d524bfc" xlink:href="tln-20260630.xsd#tln_TLB3FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_TLB3FacilityMember_019e69cb-647d-7d94-bdf1-276d6d524bfc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.125SeniorUnsecuredNotesDue2031Member_019fb0fd-5b59-754d-ba9e-36e15d6f9551" xlink:href="tln-20260630.xsd#tln_A6.125SeniorUnsecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_A6.125SeniorUnsecuredNotesDue2031Member_019fb0fd-5b59-754d-ba9e-36e15d6f9551" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.375SeniorUnsecuredNotesDue2033Member_019fb0fd-ebd8-765a-a260-5d0e4d78d5e3" xlink:href="tln-20260630.xsd#tln_A6.375SeniorUnsecuredNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_A6.375SeniorUnsecuredNotesDue2033Member_019fb0fd-ebd8-765a-a260-5d0e4d78d5e3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.25SeniorUnsecuredNotesDue2034Member_019e69cb-647d-7a5f-adde-55f1de27c1c0" xlink:href="tln-20260630.xsd#tln_A6.25SeniorUnsecuredNotesDue2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_A6.25SeniorUnsecuredNotesDue2034Member_019e69cb-647d-7a5f-adde-55f1de27c1c0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.50SeniorUnsecuredNotesDue2036Member_019e69cb-647d-770e-846b-870cbe9b9f13" xlink:href="tln-20260630.xsd#tln_A6.50SeniorUnsecuredNotesDue2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_A6.50SeniorUnsecuredNotesDue2036Member_019e69cb-647d-770e-846b-870cbe9b9f13" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PEDFA2009BBondsMember_019e69cb-647d-7422-bb19-233c9beeb41c" xlink:href="tln-20260630.xsd#tln_PEDFA2009BBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_PEDFA2009BBondsMember_019e69cb-647d-7422-bb19-233c9beeb41c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PEDFA2009CBondsMember_019e69cb-647d-7cb3-94b7-4dd4ac7b36f3" xlink:href="tln-20260630.xsd#tln_PEDFA2009CBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7291-9875-534a80d195a2" xlink:to="loc_tln_PEDFA2009CBondsMember_019e69cb-647d-7cb3-94b7-4dd4ac7b36f3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e69cb-647d-7d05-8986-f6f9bf410d2b" 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_019e69cb-647d-7685-a161-91462b17fe6c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e69cb-647d-7d05-8986-f6f9bf410d2b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7d05-8986-f6f9bf410d2b_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_019e69cb-647d-7d05-8986-f6f9bf410d2b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7d05-8986-f6f9bf410d2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7957-9cbf-0b4c6a895291" 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_019e69cb-647d-7d05-8986-f6f9bf410d2b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7957-9cbf-0b4c6a895291" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019e69cb-647d-7f2b-9bff-5de0ae5ac90e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7957-9cbf-0b4c6a895291" xlink:to="loc_us-gaap_SecuredDebtMember_019e69cb-647d-7f2b-9bff-5de0ae5ac90e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SecuredNotesMember_019e69cb-647d-76da-b1f2-e3195184776f" xlink:href="tln-20260630.xsd#tln_SecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7957-9cbf-0b4c6a895291" xlink:to="loc_tln_SecuredNotesMember_019e69cb-647d-76da-b1f2-e3195184776f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_019e69cb-647d-766b-8628-70079a8d3368" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7957-9cbf-0b4c6a895291" xlink:to="loc_us-gaap_UnsecuredDebtMember_019e69cb-647d-766b-8628-70079a8d3368" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BondsMember_019e69cb-647d-7469-8eae-cdc3716874ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7957-9cbf-0b4c6a895291" xlink:to="loc_us-gaap_BondsMember_019e69cb-647d-7469-8eae-cdc3716874ad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e69cb-647d-7843-8d0b-99d9c465837d" 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_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e69cb-647d-7843-8d0b-99d9c465837d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e69cb-647d-7e20-a7c5-59920726a235" 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_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e69cb-647d-7e20-a7c5-59920726a235" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019e69cb-647d-746a-b360-ee579d26552d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019e69cb-647d-746a-b360-ee579d26552d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019e69cb-647d-7ef2-976e-a4cfb4c03259" 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_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_LongTermDebt_019e69cb-647d-7ef2-976e-a4cfb4c03259" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019e69cb-647d-70fe-a271-d130622c86ec" 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_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_LongTermDebtCurrent_019e69cb-647d-70fe-a271-d130622c86ec" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019e69cb-647d-74a3-9f22-2e883a5dc3f0" 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_019e69cb-647d-79e4-9e11-1ba119aebe1f" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019e69cb-647d-74a3-9f22-2e883a5dc3f0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofRevolvingCreditandOtherFacilitiesDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#LongTermDebtandOtherCreditFacilitiesScheduleofRevolvingCreditandOtherFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofRevolvingCreditandOtherFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e69cb-647d-71fd-947a-4803c65a557b" 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_019e69cb-647d-7cc9-a219-4c907019a796" 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_019e69cb-647d-71fd-947a-4803c65a557b" xlink:to="loc_us-gaap_DebtInstrumentTable_019e69cb-647d-7cc9-a219-4c907019a796" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e69cb-647d-7eaa-a757-7ae3cf6a09ed" 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_019e69cb-647d-7cc9-a219-4c907019a796" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e69cb-647d-7eaa-a757-7ae3cf6a09ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7eaa-a757-7ae3cf6a09ed_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_019e69cb-647d-7eaa-a757-7ae3cf6a09ed" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-7eaa-a757-7ae3cf6a09ed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-760d-8948-97fb2b700bf2" 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_019e69cb-647d-7eaa-a757-7ae3cf6a09ed" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-760d-8948-97fb2b700bf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_019e69cb-647d-7947-979c-c4ec6bf69593" xlink:href="tln-20260630.xsd#tln_SeniorSecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-760d-8948-97fb2b700bf2" xlink:to="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_019e69cb-647d-7947-979c-c4ec6bf69593" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_StandAloneLetterOfCreditFacilityMember_019e69cb-647d-724b-98af-cd7cd129fdf3" xlink:href="tln-20260630.xsd#tln_StandAloneLetterOfCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e69cb-647d-760d-8948-97fb2b700bf2" xlink:to="loc_tln_StandAloneLetterOfCreditFacilityMember_019e69cb-647d-724b-98af-cd7cd129fdf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e69cb-647d-7cc2-8c0e-8d08b60ad984" 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_019e69cb-647d-7cc9-a219-4c907019a796" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e69cb-647d-7cc2-8c0e-8d08b60ad984" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7cc2-8c0e-8d08b60ad984_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_019e69cb-647d-7cc2-8c0e-8d08b60ad984" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7cc2-8c0e-8d08b60ad984_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7965-b1cf-d6ffdef0b625" 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_019e69cb-647d-7cc2-8c0e-8d08b60ad984" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7965-b1cf-d6ffdef0b625" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e69cb-647d-71e5-b67d-8ed6ff430778" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e69cb-647d-7965-b1cf-d6ffdef0b625" xlink:to="loc_us-gaap_LineOfCreditMember_019e69cb-647d-71e5-b67d-8ed6ff430778" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e69cb-647d-754e-857c-7db2164f7d9c" 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_019e69cb-647d-7cc9-a219-4c907019a796" xlink:to="loc_us-gaap_CreditFacilityAxis_019e69cb-647d-754e-857c-7db2164f7d9c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e69cb-647d-754e-857c-7db2164f7d9c_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_019e69cb-647d-754e-857c-7db2164f7d9c" xlink:to="loc_us-gaap_CreditFacilityDomain_019e69cb-647d-754e-857c-7db2164f7d9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e69cb-647d-7c8d-898a-534c48584bc6" 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_019e69cb-647d-754e-857c-7db2164f7d9c" xlink:to="loc_us-gaap_CreditFacilityDomain_019e69cb-647d-7c8d-898a-534c48584bc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e69cb-647d-78fd-b371-7e017518a864" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e69cb-647d-7c8d-898a-534c48584bc6" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e69cb-647d-78fd-b371-7e017518a864" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019e69cb-647d-75ec-a9fd-35c43072c189" 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_019e69cb-647d-7c8d-898a-534c48584bc6" xlink:to="loc_us-gaap_LetterOfCreditMember_019e69cb-647d-75ec-a9fd-35c43072c189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019e69cb-647d-7499-a038-3bc5c0f3e049" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e69cb-647d-71fd-947a-4803c65a557b" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019e69cb-647d-7499-a038-3bc5c0f3e049" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e69cb-647d-7881-b5e0-213271196550" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e69cb-647d-71fd-947a-4803c65a557b" xlink:to="loc_us-gaap_LineOfCredit_019e69cb-647d-7881-b5e0-213271196550" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019e69cb-647d-7fca-871a-0645318a3ee5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e69cb-647d-71fd-947a-4803c65a557b" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019e69cb-647d-7fca-871a-0645318a3ee5" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesNarrativeDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#LongTermDebtandOtherCreditFacilitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fad23-d156-71ec-a168-61345112510f" 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_019fad23-d156-737e-bbd4-a82d5af24d05" 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_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_DebtInstrumentTable_019fad23-d156-737e-bbd4-a82d5af24d05" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fad23-d156-7ff6-a9a9-edff8dfbcbad" 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_019fad23-d156-737e-bbd4-a82d5af24d05" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fad23-d156-7ff6-a9a9-edff8dfbcbad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-7ff6-a9a9-edff8dfbcbad_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_019fad23-d156-7ff6-a9a9-edff8dfbcbad" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-7ff6-a9a9-edff8dfbcbad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-72ec-a27e-41f4b74707a0" 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_019fad23-d156-7ff6-a9a9-edff8dfbcbad" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-72ec-a27e-41f4b74707a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019fad23-d156-7947-962d-88633586551b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-72ec-a27e-41f4b74707a0" xlink:to="loc_us-gaap_LineOfCreditMember_019fad23-d156-7947-962d-88633586551b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019fad24-c578-716d-9f2a-db37dfb0a281" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-72ec-a27e-41f4b74707a0" xlink:to="loc_us-gaap_SecuredDebtMember_019fad24-c578-716d-9f2a-db37dfb0a281" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_019fad24-ed54-7a1c-8189-1c76b4609907" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fad23-d156-72ec-a27e-41f4b74707a0" xlink:to="loc_us-gaap_UnsecuredDebtMember_019fad24-ed54-7a1c-8189-1c76b4609907" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_019fad23-d156-72fe-ab27-8f7be2cebf61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fad23-d156-737e-bbd4-a82d5af24d05" xlink:to="loc_us-gaap_VariableRateAxis_019fad23-d156-72fe-ab27-8f7be2cebf61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019fad23-d156-72fe-ab27-8f7be2cebf61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_019fad23-d156-72fe-ab27-8f7be2cebf61" xlink:to="loc_us-gaap_VariableRateDomain_019fad23-d156-72fe-ab27-8f7be2cebf61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019fad23-d156-7905-991f-3b9d28a00d94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_019fad23-d156-72fe-ab27-8f7be2cebf61" xlink:to="loc_us-gaap_VariableRateDomain_019fad23-d156-7905-991f-3b9d28a00d94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember_019fad23-d156-7f56-aa9e-1f2c80159de8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalFundsEffectiveSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019fad23-d156-7905-991f-3b9d28a00d94" xlink:to="loc_us-gaap_FederalFundsEffectiveSwapRateMember_019fad23-d156-7f56-aa9e-1f2c80159de8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_019faf52-170b-7694-ac8b-2ceb86619dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019fad23-d156-7905-991f-3b9d28a00d94" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_019faf52-170b-7694-ac8b-2ceb86619dc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedSecuredOvernightFinancingRateSOFRMember_019fad2d-ef06-720f-85d1-54e0bc7a4867" xlink:href="tln-20260630.xsd#tln_AdjustedSecuredOvernightFinancingRateSOFRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019fad23-d156-7905-991f-3b9d28a00d94" xlink:to="loc_tln_AdjustedSecuredOvernightFinancingRateSOFRMember_019fad2d-ef06-720f-85d1-54e0bc7a4867" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fad24-7f05-7765-bc15-d257e84e6eb8" 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_019fad23-d156-737e-bbd4-a82d5af24d05" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fad24-7f05-7765-bc15-d257e84e6eb8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7765-bc15-d257e84e6eb8_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_019fad24-7f05-7765-bc15-d257e84e6eb8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7765-bc15-d257e84e6eb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" 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_019fad24-7f05-7765-bc15-d257e84e6eb8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_019fad24-7f05-7129-8998-3c5dd96c828b" xlink:href="tln-20260630.xsd#tln_SeniorSecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:to="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_019fad24-7f05-7129-8998-3c5dd96c828b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB1FacilityMember_019fad24-c578-7721-a73e-b945f0d620df" xlink:href="tln-20260630.xsd#tln_TLB1FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:to="loc_tln_TLB1FacilityMember_019fad24-c578-7721-a73e-b945f0d620df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB2FacilityMember_019faf54-6ec5-7c44-9dbb-0ace907411d1" xlink:href="tln-20260630.xsd#tln_TLB2FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:to="loc_tln_TLB2FacilityMember_019faf54-6ec5-7c44-9dbb-0ace907411d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_StandAloneLetterOfCreditFacilityMember_019fad24-7f05-7fd1-9f59-eeff50da0bb4" xlink:href="tln-20260630.xsd#tln_StandAloneLetterOfCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:to="loc_tln_StandAloneLetterOfCreditFacilityMember_019fad24-7f05-7fd1-9f59-eeff50da0bb4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.125SeniorUnsecuredNotesDue2031Member_019fad24-ed54-7e48-82ad-557e861f588b" xlink:href="tln-20260630.xsd#tln_A6.125SeniorUnsecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:to="loc_tln_A6.125SeniorUnsecuredNotesDue2031Member_019fad24-ed54-7e48-82ad-557e861f588b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.375SeniorUnsecuredNotesDue2033Member_019fad24-ed54-7483-9aab-edf49ef2c4a5" xlink:href="tln-20260630.xsd#tln_A6.375SeniorUnsecuredNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fad24-7f05-7229-a3dc-27a36410136c" xlink:to="loc_tln_A6.375SeniorUnsecuredNotesDue2033Member_019fad24-ed54-7483-9aab-edf49ef2c4a5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fad25-5742-7547-9f0f-cc4dc032d264" 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_019fad23-d156-737e-bbd4-a82d5af24d05" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fad25-5742-7547-9f0f-cc4dc032d264" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fad25-5742-7547-9f0f-cc4dc032d264_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_019fad25-5742-7547-9f0f-cc4dc032d264" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fad25-5742-7547-9f0f-cc4dc032d264_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fad25-5742-77a2-b898-3247837bd5a1" 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_019fad25-5742-7547-9f0f-cc4dc032d264" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fad25-5742-77a2-b898-3247837bd5a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SecuredISDAsMember_019fad25-5742-7813-9547-dbded1e899ba" xlink:href="tln-20260630.xsd#tln_SecuredISDAsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fad25-5742-77a2-b898-3247837bd5a1" xlink:to="loc_tln_SecuredISDAsMember_019fad25-5742-7813-9547-dbded1e899ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019fad23-d156-7e5f-a788-122d2a5918bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019fad23-d156-7e5f-a788-122d2a5918bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019fad24-7f05-7199-aad2-f0ce9b31dce2" 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_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019fad24-7f05-7199-aad2-f0ce9b31dce2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_019fad24-c578-73a7-87cf-d0738583c0d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_InterestAndDebtExpense_019fad24-c578-73a7-87cf-d0738583c0d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019fad24-ed54-7624-8434-30799caaebad" 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_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019fad24-ed54-7624-8434-30799caaebad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_019fad24-ed54-72d4-8c4c-acadfe2f45a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_019fad24-ed54-72d4-8c4c-acadfe2f45a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019fad25-5742-77f2-bef4-f1d6020e5330" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019fad25-5742-77f2-bef4-f1d6020e5330" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019faf6d-6245-7496-ab59-7f5f8959d535" 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_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019faf6d-6245-7496-ab59-7f5f8959d535" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnRepurchaseOfDebtInstrument_019fcda9-d557-7bdb-8147-b15469d7286e" 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_019fad23-d156-71ec-a168-61345112510f" xlink:to="loc_us-gaap_GainLossOnRepurchaseOfDebtInstrument_019fcda9-d557-7bdb-8147-b15469d7286e" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/FairValueScheduleofRecurringFairValueMeasurementsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#FairValueScheduleofRecurringFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/FairValueScheduleofRecurringFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e69cb-647d-7302-98f4-70e0e8e73c61" 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_019e69cb-647d-791d-a5aa-9580ee27b25d" 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_019e69cb-647d-7302-98f4-70e0e8e73c61" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e69cb-647d-791d-a5aa-9580ee27b25d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e69cb-647d-7dac-bfb0-b2015aeb15a8" 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_019e69cb-647d-791d-a5aa-9580ee27b25d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e69cb-647d-7dac-bfb0-b2015aeb15a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e69cb-647d-7dac-bfb0-b2015aeb15a8_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_019e69cb-647d-7dac-bfb0-b2015aeb15a8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e69cb-647d-7dac-bfb0-b2015aeb15a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e69cb-647d-7504-be51-bf5f344b75cd" 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_019e69cb-647d-7dac-bfb0-b2015aeb15a8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e69cb-647d-7504-be51-bf5f344b75cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e69cb-647d-72fa-859a-c0db722c922d" 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_019e69cb-647d-7504-be51-bf5f344b75cd" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e69cb-647d-72fa-859a-c0db722c922d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e69cb-647d-762a-a581-d8048a15195f" 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_019e69cb-647d-7504-be51-bf5f344b75cd" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e69cb-647d-762a-a581-d8048a15195f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019e69cb-647d-702d-acbc-3f6352775dc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e69cb-647d-7504-be51-bf5f344b75cd" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019e69cb-647d-702d-acbc-3f6352775dc5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7a62-8e9f-db522f59d83d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e69cb-647d-791d-a5aa-9580ee27b25d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7a62-8e9f-db522f59d83d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7a62-8e9f-db522f59d83d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7a62-8e9f-db522f59d83d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-7a62-8e9f-db522f59d83d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-70c9-ba6c-a1e05e64b23c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e69cb-647d-7a62-8e9f-db522f59d83d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-70c9-ba6c-a1e05e64b23c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_019e69cb-647d-7347-bc8c-6ba4073ae324" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-70c9-ba6c-a1e05e64b23c" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_019e69cb-647d-7347-bc8c-6ba4073ae324" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_019e69cb-647d-76c5-8e2e-e29a5bbe1e92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-70c9-ba6c-a1e05e64b23c" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_019e69cb-647d-76c5-8e2e-e29a5bbe1e92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019e69cb-647d-737e-9b49-9196983e65fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e69cb-647d-70c9-ba6c-a1e05e64b23c" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019e69cb-647d-737e-9b49-9196983e65fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-7df0-85fb-6d7092087354" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e69cb-647d-791d-a5aa-9580ee27b25d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e69cb-647d-7df0-85fb-6d7092087354" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7df0-85fb-6d7092087354_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_019e69cb-647d-7df0-85fb-6d7092087354" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7df0-85fb-6d7092087354_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7643-a784-f712ea38936a" 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_019e69cb-647d-7df0-85fb-6d7092087354" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7643-a784-f712ea38936a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e69cb-647d-74b4-8f2c-b39f0bfb646b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7643-a784-f712ea38936a" xlink:to="loc_us-gaap_CommodityContractMember_019e69cb-647d-74b4-8f2c-b39f0bfb646b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019e69cb-647d-76a1-8d90-582c0cec5217" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e69cb-647d-7643-a784-f712ea38936a" xlink:to="loc_us-gaap_InterestRateContractMember_019e69cb-647d-76a1-8d90-582c0cec5217" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" 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_019e69cb-647d-7302-98f4-70e0e8e73c61" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e69cb-647d-7d86-b631-bcc18bc106dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e69cb-647d-7d86-b631-bcc18bc106dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_019e69cb-647d-77c0-ab6e-5f15d6447ef0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_019e69cb-647d-77c0-ab6e-5f15d6447ef0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019e69cb-647d-75e4-8c0a-e9820b55742d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019e69cb-647d-75e4-8c0a-e9820b55742d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReceivablesPayablesNetFairValue_019e69cb-647d-76c0-9663-e1930366a6b0" xlink:href="tln-20260630.xsd#tln_ReceivablesPayablesNetFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_tln_ReceivablesPayablesNetFairValue_019e69cb-647d-76c0-9663-e1930366a6b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_019e69cb-647d-7888-96da-75809c4443df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_019e69cb-647d-7888-96da-75809c4443df" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_019e69cb-647d-72cd-aa2a-a71e84a8889d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_019e69cb-647d-72cd-aa2a-a71e84a8889d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_019e69cb-647d-7c32-9ca1-e33ebcd26bef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_019e69cb-647d-7c32-9ca1-e33ebcd26bef" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e69cb-647d-7ca6-bf8a-bc374b46d9a8" 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_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_DerivativeAssets_019e69cb-647d-7ca6-bf8a-bc374b46d9a8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019e69cb-647d-7c03-88a6-0bef8d4ceb72" 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_019e69cb-647d-7889-bf19-2aa990f7873d" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019e69cb-647d-7c03-88a6-0bef8d4ceb72" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e69cb-647d-70d1-a281-bc6efcc11d23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e69cb-647d-7302-98f4-70e0e8e73c61" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e69cb-647d-70d1-a281-bc6efcc11d23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_019e69cb-647d-7ed2-86fa-fb26b0426e19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e69cb-647d-70d1-a281-bc6efcc11d23" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_019e69cb-647d-7ed2-86fa-fb26b0426e19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_019e69cb-647d-7ce2-8317-5a3c9f47a89c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e69cb-647d-70d1-a281-bc6efcc11d23" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_019e69cb-647d-7ce2-8317-5a3c9f47a89c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e69cb-647d-7edb-9500-12e5625180cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e69cb-647d-70d1-a281-bc6efcc11d23" xlink:to="loc_us-gaap_DerivativeLiabilities_019e69cb-647d-7edb-9500-12e5625180cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_019e69cb-647d-7258-921a-2666dab214d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019e69cb-647d-70d1-a281-bc6efcc11d23" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_019e69cb-647d-7258-921a-2666dab214d0" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockBasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" 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_019e69cb-6547-7b78-8687-3051ca46457c" 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_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e69cb-6547-7b78-8687-3051ca46457c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e69cb-6547-7c53-81f1-7fe78e3c7daf" 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_019e69cb-6547-7b78-8687-3051ca46457c" xlink:to="loc_us-gaap_AwardTypeAxis_019e69cb-6547-7c53-81f1-7fe78e3c7daf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7c53-81f1-7fe78e3c7daf_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_019e69cb-6547-7c53-81f1-7fe78e3c7daf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7c53-81f1-7fe78e3c7daf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7cad-a87d-002ed3585268" 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_019e69cb-6547-7c53-81f1-7fe78e3c7daf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7cad-a87d-002ed3585268" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-74a7-8276-17ea93993942" 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_019e69cb-6547-7cad-a87d-002ed3585268" xlink:to="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-74a7-8276-17ea93993942" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-7cf2-9d36-474e5fbf4187" 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_019e69cb-6547-7cad-a87d-002ed3585268" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-7cf2-9d36-474e5fbf4187" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019e69cb-6547-725d-a3a3-44e5b009b95c" 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_019e69cb-6547-7b78-8687-3051ca46457c" xlink:to="loc_us-gaap_VestingAxis_019e69cb-6547-725d-a3a3-44e5b009b95c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019e69cb-6547-725d-a3a3-44e5b009b95c_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_019e69cb-6547-725d-a3a3-44e5b009b95c" xlink:to="loc_us-gaap_VestingDomain_019e69cb-6547-725d-a3a3-44e5b009b95c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019e69cb-6547-70de-b86c-979a7a147dbe" 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_019e69cb-6547-725d-a3a3-44e5b009b95c" xlink:to="loc_us-gaap_VestingDomain_019e69cb-6547-70de-b86c-979a7a147dbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CliffVestingScheduleMember_019e69cb-6547-7e32-b927-f59f51dc83b4" xlink:href="tln-20260630.xsd#tln_CliffVestingScheduleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e69cb-6547-70de-b86c-979a7a147dbe" xlink:to="loc_tln_CliffVestingScheduleMember_019e69cb-6547-7e32-b927-f59f51dc83b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_RatableVestingScheduleMember_019e69cb-6547-7214-8ee0-3cb942c46105" xlink:href="tln-20260630.xsd#tln_RatableVestingScheduleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e69cb-6547-70de-b86c-979a7a147dbe" xlink:to="loc_tln_RatableVestingScheduleMember_019e69cb-6547-7214-8ee0-3cb942c46105" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e69cb-6547-7db0-b9d4-dc5da77e2642" 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_019e69cb-6547-7b78-8687-3051ca46457c" xlink:to="loc_srt_RangeAxis_019e69cb-6547-7db0-b9d4-dc5da77e2642" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-6547-7db0-b9d4-dc5da77e2642_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_019e69cb-6547-7db0-b9d4-dc5da77e2642" xlink:to="loc_srt_RangeMember_019e69cb-6547-7db0-b9d4-dc5da77e2642_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-6547-7e8f-842b-932b96f53222" 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_019e69cb-6547-7db0-b9d4-dc5da77e2642" xlink:to="loc_srt_RangeMember_019e69cb-6547-7e8f-842b-932b96f53222" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e69cb-6547-7229-91e8-c73c735e9f7b" 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_019e69cb-6547-7e8f-842b-932b96f53222" xlink:to="loc_srt_MinimumMember_019e69cb-6547-7229-91e8-c73c735e9f7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e69cb-6547-7a2b-b35a-c6a8bdc50128" 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_019e69cb-6547-7e8f-842b-932b96f53222" xlink:to="loc_srt_MaximumMember_019e69cb-6547-7a2b-b35a-c6a8bdc50128" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019e69cb-6547-73be-ab60-d2c3f28a5bb9" 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_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019e69cb-6547-73be-ab60-d2c3f28a5bb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e69cb-6547-7dcb-a7e0-e9164f5a1ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e69cb-6547-7dcb-a7e0-e9164f5a1ca8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CashSettlementPercentage_019e69cb-6547-7b49-bba5-ff637402ad91" xlink:href="tln-20260630.xsd#tln_CashSettlementPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_tln_CashSettlementPercentage_019e69cb-6547-7b49-bba5-ff637402ad91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent_019e69cb-6547-73bc-8e0b-cbf44c7017c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent_019e69cb-6547-73bc-8e0b-cbf44c7017c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationCashFlowEffectCashUsedToSettleAwards_019fb101-9f0b-7194-9c8d-0ab12d1920f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationCashFlowEffectCashUsedToSettleAwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationCashFlowEffectCashUsedToSettleAwards_019fb101-9f0b-7194-9c8d-0ab12d1920f3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedAwardsSharesIssuesUponVesting_019faf7a-ef5f-79c4-b301-f021172017ce" xlink:href="tln-20260630.xsd#tln_EquityClassifiedAwardsSharesIssuesUponVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_tln_EquityClassifiedAwardsSharesIssuesUponVesting_019faf7a-ef5f-79c4-b301-f021172017ce" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019fb102-c874-7564-8cc3-5ecfd2aea88b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7315-9a1b-4d2ebae8d3ce" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019fb102-c874-7564-8cc3-5ecfd2aea88b" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofNonvestedPerformanceStockUnitsandRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockBasedCompensationScheduleofNonvestedPerformanceStockUnitsandRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofNonvestedPerformanceStockUnitsandRestrictedStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-72b3-829b-003aa2029f34" 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_019e69cb-6547-7efc-8be9-f037f29783d8" 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_019e69cb-6547-72b3-829b-003aa2029f34" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e69cb-6547-7efc-8be9-f037f29783d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e69cb-6547-73dc-8c7f-ce1f599a6bab" 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_019e69cb-6547-7efc-8be9-f037f29783d8" xlink:to="loc_us-gaap_AwardTypeAxis_019e69cb-6547-73dc-8c7f-ce1f599a6bab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-73dc-8c7f-ce1f599a6bab_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_019e69cb-6547-73dc-8c7f-ce1f599a6bab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-73dc-8c7f-ce1f599a6bab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7ff3-a447-94c0481623de" 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_019e69cb-6547-73dc-8c7f-ce1f599a6bab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7ff3-a447-94c0481623de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7c23-9e90-e9c5fce7eb63" 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_019e69cb-6547-7ff3-a447-94c0481623de" xlink:to="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7c23-9e90-e9c5fce7eb63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedPerformanceSharesMember_019e69cb-6547-781f-aecc-cfcbe4ae8e41" xlink:href="tln-20260630.xsd#tln_LiabilityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7c23-9e90-e9c5fce7eb63" xlink:to="loc_tln_LiabilityClassifiedPerformanceSharesMember_019e69cb-6547-781f-aecc-cfcbe4ae8e41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedPerformanceSharesMember_019e69cb-6547-7da9-b740-3a704d644e11" xlink:href="tln-20260630.xsd#tln_EquityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7c23-9e90-e9c5fce7eb63" xlink:to="loc_tln_EquityClassifiedPerformanceSharesMember_019e69cb-6547-7da9-b740-3a704d644e11" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-70b9-ae63-b7efadca0209" 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_019e69cb-6547-7ff3-a447-94c0481623de" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-70b9-ae63-b7efadca0209" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019e69cb-6547-73f6-a254-d58ab35de966" xlink:href="tln-20260630.xsd#tln_LiabilityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-70b9-ae63-b7efadca0209" xlink:to="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019e69cb-6547-73f6-a254-d58ab35de966" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019e69cb-6547-77f6-bb19-87da894cfe6d" xlink:href="tln-20260630.xsd#tln_EquityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-70b9-ae63-b7efadca0209" xlink:to="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019e69cb-6547-77f6-bb19-87da894cfe6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e69cb-6547-76bf-a45d-4c8d89e792cd" 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_019e69cb-6547-7efc-8be9-f037f29783d8" xlink:to="loc_srt_RangeAxis_019e69cb-6547-76bf-a45d-4c8d89e792cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-6547-76bf-a45d-4c8d89e792cd_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_019e69cb-6547-76bf-a45d-4c8d89e792cd" xlink:to="loc_srt_RangeMember_019e69cb-6547-76bf-a45d-4c8d89e792cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-6547-7612-9aae-f48e321deaca" 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_019e69cb-6547-76bf-a45d-4c8d89e792cd" xlink:to="loc_srt_RangeMember_019e69cb-6547-7612-9aae-f48e321deaca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e69cb-6547-76cb-b94b-2b3417dd108e" 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_019e69cb-6547-7612-9aae-f48e321deaca" xlink:to="loc_srt_MinimumMember_019e69cb-6547-76cb-b94b-2b3417dd108e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e69cb-6547-742a-993f-3a4b75ed4b96" 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_019e69cb-6547-7612-9aae-f48e321deaca" xlink:to="loc_srt_MaximumMember_019e69cb-6547-742a-993f-3a4b75ed4b96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e69cb-6547-7663-b98f-7765cd7e693e" 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_019e69cb-6547-72b3-829b-003aa2029f34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e69cb-6547-7663-b98f-7765cd7e693e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e69cb-6547-7380-982a-90b990a1b624" 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_019e69cb-6547-7663-b98f-7765cd7e693e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e69cb-6547-7380-982a-90b990a1b624" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e69cb-6547-7d56-ae27-917465bf2a42" 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_019e69cb-6547-7663-b98f-7765cd7e693e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e69cb-6547-7d56-ae27-917465bf2a42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019f8840-c8d6-72ff-a1ef-738167ecb725" 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_019e69cb-6547-7663-b98f-7765cd7e693e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019f8840-c8d6-72ff-a1ef-738167ecb725" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019f8840-79ce-77c6-93b5-5140455985c3" 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_019e69cb-6547-7663-b98f-7765cd7e693e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019f8840-79ce-77c6-93b5-5140455985c3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e69cb-6547-74b1-81c2-d0d696fd2b51" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e69cb-6547-7779-9cfd-a93e4de2deb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-72b3-829b-003aa2029f34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e69cb-6547-7779-9cfd-a93e4de2deb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e69cb-6547-79c1-91f4-7722bfe01577" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e69cb-6547-7779-9cfd-a93e4de2deb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e69cb-6547-79c1-91f4-7722bfe01577" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e69cb-6547-747a-be2f-81b023579867" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e69cb-6547-7779-9cfd-a93e4de2deb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e69cb-6547-747a-be2f-81b023579867" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019f8840-c8d6-7212-aefd-e758fb9f2d3d" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e69cb-6547-7779-9cfd-a93e4de2deb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019f8840-c8d6-7212-aefd-e758fb9f2d3d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019f8840-c8d6-7022-92c0-85be1ca538ff" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e69cb-6547-7779-9cfd-a93e4de2deb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019f8840-c8d6-7022-92c0-85be1ca538ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e69cb-6547-71ea-8702-6c0dcfb206c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsActualAmountOfAwardsEarnedPercentage_019e69cb-6547-7dba-935b-bba401ca881b" xlink:href="tln-20260630.xsd#tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsActualAmountOfAwardsEarnedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-72b3-829b-003aa2029f34" xlink:to="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsActualAmountOfAwardsEarnedPercentage_019e69cb-6547-7dba-935b-bba401ca881b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedBasedOnStockPricePerformanceNumber_019e69cb-6547-7c54-aaf3-f2975d3c8344" xlink:href="tln-20260630.xsd#tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedBasedOnStockPricePerformanceNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-72b3-829b-003aa2029f34" xlink:to="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedBasedOnStockPricePerformanceNumber_019e69cb-6547-7c54-aaf3-f2975d3c8344" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofSignificantInputsandAssumptionsofFairValueDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockBasedCompensationScheduleofSignificantInputsandAssumptionsofFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofSignificantInputsandAssumptionsofFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-781d-a95a-1d15d4eb6cdf" 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_019e69cb-6547-76d7-930b-54898704f549" 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_019e69cb-6547-781d-a95a-1d15d4eb6cdf" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e69cb-6547-76d7-930b-54898704f549" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e69cb-6547-73f5-b465-1d3f3a1dd58f" 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_019e69cb-6547-76d7-930b-54898704f549" xlink:to="loc_us-gaap_AwardTypeAxis_019e69cb-6547-73f5-b465-1d3f3a1dd58f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-73f5-b465-1d3f3a1dd58f_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_019e69cb-6547-73f5-b465-1d3f3a1dd58f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-73f5-b465-1d3f3a1dd58f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7916-bb72-37420914152b" 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_019e69cb-6547-73f5-b465-1d3f3a1dd58f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7916-bb72-37420914152b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7045-b779-0113e04a8b2c" 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_019e69cb-6547-7916-bb72-37420914152b" xlink:to="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7045-b779-0113e04a8b2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e69cb-6547-79a9-ac46-15641fddba8c" 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_019e69cb-6547-76d7-930b-54898704f549" xlink:to="loc_srt_RangeAxis_019e69cb-6547-79a9-ac46-15641fddba8c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-6547-79a9-ac46-15641fddba8c_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_019e69cb-6547-79a9-ac46-15641fddba8c" xlink:to="loc_srt_RangeMember_019e69cb-6547-79a9-ac46-15641fddba8c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e69cb-6547-7890-86be-14b39026fddc" 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_019e69cb-6547-79a9-ac46-15641fddba8c" xlink:to="loc_srt_RangeMember_019e69cb-6547-7890-86be-14b39026fddc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e69cb-6547-7b72-b488-a89842fe4d22" 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_019e69cb-6547-7890-86be-14b39026fddc" xlink:to="loc_srt_MinimumMember_019e69cb-6547-7b72-b488-a89842fe4d22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e69cb-6547-7ae9-b0c9-ab20707f3bb0" 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_019e69cb-6547-7890-86be-14b39026fddc" xlink:to="loc_srt_MaximumMember_019e69cb-6547-7ae9-b0c9-ab20707f3bb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_019e69cb-6547-7a39-b034-e3e6ef640b78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-781d-a95a-1d15d4eb6cdf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_019e69cb-6547-7a39-b034-e3e6ef640b78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019e69cb-6547-7c3b-a358-38644a98753e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-781d-a95a-1d15d4eb6cdf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019e69cb-6547-7c3b-a358-38644a98753e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e69cb-6547-7069-81a5-f63d9ed4c387" 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_019e69cb-6547-781d-a95a-1d15d4eb6cdf" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e69cb-6547-7069-81a5-f63d9ed4c387" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_019e69cb-6547-7a6b-b3aa-ab703688fbad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-781d-a95a-1d15d4eb6cdf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_019e69cb-6547-7a6b-b3aa-ab703688fbad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_019e69cb-6547-7a05-9c8c-47ac7fd268ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-781d-a95a-1d15d4eb6cdf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_019e69cb-6547-7a05-9c8c-47ac7fd268ee" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockBasedCompensationScheduleofStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofStockbasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7e13-ba0e-6577e98daa66" 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_019e69cb-6547-71f3-9cf7-3cfd2cb06a7c" 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_019e69cb-6547-7e13-ba0e-6577e98daa66" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e69cb-6547-71f3-9cf7-3cfd2cb06a7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e69cb-6547-7c31-a04a-c203d8a8f7a9" 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_019e69cb-6547-71f3-9cf7-3cfd2cb06a7c" xlink:to="loc_us-gaap_AwardTypeAxis_019e69cb-6547-7c31-a04a-c203d8a8f7a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7c31-a04a-c203d8a8f7a9_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_019e69cb-6547-7c31-a04a-c203d8a8f7a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7c31-a04a-c203d8a8f7a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7fba-afc2-773fe6c4170b" 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_019e69cb-6547-7c31-a04a-c203d8a8f7a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7fba-afc2-773fe6c4170b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedAwardsMember_019e69cb-6547-7984-a3a4-e62964d5aaac" xlink:href="tln-20260630.xsd#tln_LiabilityClassifiedAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7fba-afc2-773fe6c4170b" xlink:to="loc_tln_LiabilityClassifiedAwardsMember_019e69cb-6547-7984-a3a4-e62964d5aaac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedAwardsMember_019e69cb-6547-7c6d-8b45-23761a1653de" xlink:href="tln-20260630.xsd#tln_EquityClassifiedAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7fba-afc2-773fe6c4170b" xlink:to="loc_tln_EquityClassifiedAwardsMember_019e69cb-6547-7c6d-8b45-23761a1653de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e69cb-6547-746d-90cf-79dab4295f9c" 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_019e69cb-6547-7e13-ba0e-6577e98daa66" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e69cb-6547-746d-90cf-79dab4295f9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_019e69cb-6547-76a2-898e-c2e9afeabe6f" 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_019e69cb-6547-7e13-ba0e-6577e98daa66" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_019e69cb-6547-76a2-898e-c2e9afeabe6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_019e69cb-6547-7730-93ac-97c59ed66ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7e13-ba0e-6577e98daa66" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_019e69cb-6547-7730-93ac-97c59ed66ca6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofUnrecognizedStockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockBasedCompensationScheduleofUnrecognizedStockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofUnrecognizedStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e69cb-6547-7223-91ba-94331278e593" 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_019e69cb-6547-75e2-8483-cff085b49686" 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_019e69cb-6547-7223-91ba-94331278e593" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e69cb-6547-75e2-8483-cff085b49686" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e69cb-6547-75e2-a55c-d9a33eada53e" 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_019e69cb-6547-75e2-8483-cff085b49686" xlink:to="loc_us-gaap_AwardTypeAxis_019e69cb-6547-75e2-a55c-d9a33eada53e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-75e2-a55c-d9a33eada53e_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_019e69cb-6547-75e2-a55c-d9a33eada53e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-75e2-a55c-d9a33eada53e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7337-9434-3891938930dd" 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_019e69cb-6547-75e2-a55c-d9a33eada53e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7337-9434-3891938930dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedPerformanceSharesMember_019e69cb-6547-7f74-aa01-27a1ed7096cb" xlink:href="tln-20260630.xsd#tln_LiabilityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7337-9434-3891938930dd" xlink:to="loc_tln_LiabilityClassifiedPerformanceSharesMember_019e69cb-6547-7f74-aa01-27a1ed7096cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedPerformanceSharesMember_019e69cb-6547-73f8-a515-a0b4089ef1ab" xlink:href="tln-20260630.xsd#tln_EquityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7337-9434-3891938930dd" xlink:to="loc_tln_EquityClassifiedPerformanceSharesMember_019e69cb-6547-73f8-a515-a0b4089ef1ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019e69cb-6547-735a-a9a9-3dcac8ad97ce" xlink:href="tln-20260630.xsd#tln_LiabilityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7337-9434-3891938930dd" xlink:to="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019e69cb-6547-735a-a9a9-3dcac8ad97ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019e69cb-6547-7f63-a339-692a57a05dc8" xlink:href="tln-20260630.xsd#tln_EquityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e69cb-6547-7337-9434-3891938930dd" xlink:to="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019e69cb-6547-7f63-a339-692a57a05dc8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019e69cb-6547-7bcc-aac9-52fe451a83d3" 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_019e69cb-6547-7223-91ba-94331278e593" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019e69cb-6547-7bcc-aac9-52fe451a83d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e69cb-6547-7c3e-a9b4-a12db9a3b5c7" 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_019e69cb-6547-7223-91ba-94331278e593" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e69cb-6547-7c3e-a9b4-a12db9a3b5c7" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/EarningsPerShareScheduleofEarningsPerShareDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#EarningsPerShareScheduleofEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/EarningsPerShareScheduleofEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fa28c-eb5f-7efd-8c64-d75339b5f0a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fa28c-eb5f-7f62-9116-c2ce7374348f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fa28c-eb5f-7efd-8c64-d75339b5f0a6" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fa28c-eb5f-7f62-9116-c2ce7374348f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fa28c-eb5f-7c85-a3c4-ed307e0ae5c1" 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_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fa28c-eb5f-7f62-9116-c2ce7374348f" xlink:to="loc_us-gaap_AwardTypeAxis_019fa28c-eb5f-7c85-a3c4-ed307e0ae5c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fa28c-eb5f-7c85-a3c4-ed307e0ae5c1_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_019fa28c-eb5f-7c85-a3c4-ed307e0ae5c1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fa28c-eb5f-7c85-a3c4-ed307e0ae5c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fa28c-eb5f-765d-ab65-9de5088a0006" 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_019fa28c-eb5f-7c85-a3c4-ed307e0ae5c1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fa28c-eb5f-765d-ab65-9de5088a0006" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fa28c-eb5f-743b-bcaf-d225c82e9549" 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_019fa28c-eb5f-765d-ab65-9de5088a0006" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fa28c-eb5f-743b-bcaf-d225c82e9549" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019fa28c-eb5f-7065-872f-e6fe9a81922e" 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_019fa28c-eb5f-765d-ab65-9de5088a0006" xlink:to="loc_us-gaap_PerformanceSharesMember_019fa28c-eb5f-7065-872f-e6fe9a81922e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019e69cb-6547-7756-a334-2523b8999761" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fa28c-eb5f-7efd-8c64-d75339b5f0a6" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019e69cb-6547-7756-a334-2523b8999761" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fcdab-5912-70de-ab12-5f6cee13c35c" 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_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019e69cb-6547-7756-a334-2523b8999761" xlink:to="loc_us-gaap_NetIncomeLoss_019fcdab-5912-70de-ab12-5f6cee13c35c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e69cb-6547-779c-82c6-71cffbb9ada0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fa28c-eb5f-7efd-8c64-d75339b5f0a6" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e69cb-6547-779c-82c6-71cffbb9ada0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e69cb-6547-7fca-9197-3f9b5b499668" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e69cb-6547-779c-82c6-71cffbb9ada0" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e69cb-6547-7fca-9197-3f9b5b499668" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019fa28c-eb5f-7772-a48e-2ef2e0f5ee13" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e69cb-6547-779c-82c6-71cffbb9ada0" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019fa28c-eb5f-7772-a48e-2ef2e0f5ee13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e69cb-6547-712a-bb5b-f41e8da6d240" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e69cb-6547-779c-82c6-71cffbb9ada0" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e69cb-6547-712a-bb5b-f41e8da6d240" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e69cb-6547-7d5f-a8ab-67f6a4da2bd4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fa28c-eb5f-7efd-8c64-d75339b5f0a6" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e69cb-6547-7d5f-a8ab-67f6a4da2bd4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e69cb-6547-7674-b10f-4331d8a4f7c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fa28c-eb5f-7efd-8c64-d75339b5f0a6" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e69cb-6547-7674-b10f-4331d8a4f7c9" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/EarningsPerShareNarrativeDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#EarningsPerShareNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/EarningsPerShareNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e69cb-6547-7afb-92ee-9419c55234dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e69cb-6547-7d33-92ae-8743dd3c0aae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e69cb-6547-7afb-92ee-9419c55234dc" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e69cb-6547-7d33-92ae-8743dd3c0aae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e69cb-6547-7b15-a0ba-110f57d51a78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e69cb-6547-7d33-92ae-8743dd3c0aae" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e69cb-6547-7b15-a0ba-110f57d51a78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e69cb-6547-7b15-a0ba-110f57d51a78_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e69cb-6547-7b15-a0ba-110f57d51a78" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e69cb-6547-7b15-a0ba-110f57d51a78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e69cb-6547-7cb2-aa62-9708e89973a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e69cb-6547-7b15-a0ba-110f57d51a78" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e69cb-6547-7cb2-aa62-9708e89973a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7f23-8f8b-9534c0e8f81e" 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_AntidilutiveSecuritiesNameDomain_019e69cb-6547-7cb2-aa62-9708e89973a1" xlink:to="loc_us-gaap_PerformanceSharesMember_019e69cb-6547-7f23-8f8b-9534c0e8f81e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-761f-869d-202c1a723628" 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_AntidilutiveSecuritiesNameDomain_019e69cb-6547-7cb2-aa62-9708e89973a1" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e69cb-6547-761f-869d-202c1a723628" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e69cb-6547-7706-b733-b9f7c25cdaa6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e69cb-6547-7afb-92ee-9419c55234dc" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e69cb-6547-7706-b733-b9f7c25cdaa6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockholdersEquityChangesinAOCIDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockholdersEquityChangesinAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockholdersEquityChangesinAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e69cb-6547-792f-937d-0a9d98e047b7" 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_019e69cb-6547-71d3-855c-ba1d7170315b" 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_019e69cb-6547-792f-937d-0a9d98e047b7" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e69cb-6547-71d3-855c-ba1d7170315b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e69cb-6547-7f82-a293-ffc1d76da1f0" 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_019e69cb-6547-71d3-855c-ba1d7170315b" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e69cb-6547-7f82-a293-ffc1d76da1f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e69cb-6547-7f82-a293-ffc1d76da1f0_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_019e69cb-6547-7f82-a293-ffc1d76da1f0" xlink:to="loc_us-gaap_EquityComponentDomain_019e69cb-6547-7f82-a293-ffc1d76da1f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e69cb-6547-7c50-8fc2-af5d7e089006" 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_019e69cb-6547-7f82-a293-ffc1d76da1f0" xlink:to="loc_us-gaap_EquityComponentDomain_019e69cb-6547-7c50-8fc2-af5d7e089006" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e69cb-6547-7c1f-ab2c-72905b9906f6" 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_019e69cb-6547-7c50-8fc2-af5d7e089006" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e69cb-6547-7c1f-ab2c-72905b9906f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e69cb-6547-792f-937d-0a9d98e047b7" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-6547-7c3c-970b-bec1a051ba6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-6547-7c3c-970b-bec1a051ba6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_019e69cb-6547-748a-bf2b-c481e169cd97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_019e69cb-6547-748a-bf2b-c481e169cd97" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_019e69cb-6547-7f5f-bfc7-294f85876ea3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_019e69cb-6547-7f5f-bfc7-294f85876ea3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTax_019e69cb-6547-7f95-bf78-3a398ee1497a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTax_019e69cb-6547-7f95-bf78-3a398ee1497a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e69cb-6547-761a-b2f0-736c26af0909" 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_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e69cb-6547-7a8f-a8dd-4f5f50f5559a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e69cb-6547-761a-b2f0-736c26af0909" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-6547-7d5c-aaf9-6de2af644b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockholdersEquityComponentsofAOCIDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#StockholdersEquityComponentsofAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockholdersEquityComponentsofAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e69cb-6547-7c98-a5ba-4459bdb71d26" 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_019e69cb-6547-7517-8896-2f514e633f43" 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_019e69cb-6547-7c98-a5ba-4459bdb71d26" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e69cb-6547-7517-8896-2f514e633f43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e69cb-6547-7afd-a2c0-613c7ec8de36" 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_019e69cb-6547-7517-8896-2f514e633f43" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e69cb-6547-7afd-a2c0-613c7ec8de36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e69cb-6547-7afd-a2c0-613c7ec8de36_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_019e69cb-6547-7afd-a2c0-613c7ec8de36" xlink:to="loc_us-gaap_EquityComponentDomain_019e69cb-6547-7afd-a2c0-613c7ec8de36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e69cb-6547-778f-abc9-5deb3e28abe8" 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_019e69cb-6547-7afd-a2c0-613c7ec8de36" xlink:to="loc_us-gaap_EquityComponentDomain_019e69cb-6547-778f-abc9-5deb3e28abe8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e69cb-6547-71ad-b6fa-722a8caefe88" 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_019e69cb-6547-778f-abc9-5deb3e28abe8" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e69cb-6547-71ad-b6fa-722a8caefe88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_019e69cb-6547-7b6a-9aeb-07f96d2104c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e69cb-6547-71ad-b6fa-722a8caefe88" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_019e69cb-6547-7b6a-9aeb-07f96d2104c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_019e69cb-6547-738a-8613-5d6c0397a60f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e69cb-6547-71ad-b6fa-722a8caefe88" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_019e69cb-6547-738a-8613-5d6c0397a60f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_019e69cb-6547-7412-9926-ba8c02e2cda3" 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_019e69cb-6547-71ad-b6fa-722a8caefe88" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_019e69cb-6547-7412-9926-ba8c02e2cda3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-6547-7a01-928c-1288a479d39f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e69cb-6547-7c98-a5ba-4459bdb71d26" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e69cb-6547-7a01-928c-1288a479d39f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestituresNarrativeDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AcquisitionsandDivestituresNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestituresNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019fa2bc-afeb-7f35-a33b-717cfa83bafb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fa2bc-afeb-77cf-bbaa-a6c08992ab35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fa2bc-afeb-7f35-a33b-717cfa83bafb" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fa2bc-afeb-77cf-bbaa-a6c08992ab35" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019fa2bc-afeb-7a8b-a93e-cda22629b8de" 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_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fa2bc-afeb-77cf-bbaa-a6c08992ab35" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019fa2bc-afeb-7a8b-a93e-cda22629b8de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019fa2bc-afeb-7a8b-a93e-cda22629b8de_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_019fa2bc-afeb-7a8b-a93e-cda22629b8de" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019fa2bc-afeb-7a8b-a93e-cda22629b8de_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019fa2bc-afeb-7f76-b06d-2a0f2f23a4ac" 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_019fa2bc-afeb-7a8b-a93e-cda22629b8de" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019fa2bc-afeb-7f76-b06d-2a0f2f23a4ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CornerstoneAcquisitionMember_019fa2bc-afeb-71a2-a6e0-cb1d7ab64da3" xlink:href="tln-20260630.xsd#tln_CornerstoneAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019fa2bc-afeb-7f76-b06d-2a0f2f23a4ac" xlink:to="loc_tln_CornerstoneAcquisitionMember_019fa2bc-afeb-71a2-a6e0-cb1d7ab64da3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_IncreaseInPowerGenerationCapacity_019faf41-4522-7ab0-8d93-8fae9cb9b859" xlink:href="tln-20260630.xsd#tln_IncreaseInPowerGenerationCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fa2bc-afeb-7f35-a33b-717cfa83bafb" xlink:to="loc_tln_IncreaseInPowerGenerationCapacity_019faf41-4522-7ab0-8d93-8fae9cb9b859" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019fa2bc-afeb-7af3-8d28-cf0e1c1246a8" 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_BusinessAcquisitionLineItems_019fa2bc-afeb-7f35-a33b-717cfa83bafb" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019fa2bc-afeb-7af3-8d28-cf0e1c1246a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_019fa2bd-0e7e-72d6-bbe6-d694d9ac1b72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fa2bc-afeb-7f35-a33b-717cfa83bafb" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_019fa2bd-0e7e-72d6-bbe6-d694d9ac1b72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BusinessCombinationDeferredFinancingCostsExpense_019fb52c-01d1-7cd0-8051-2d4737ab9dd6" xlink:href="tln-20260630.xsd#tln_BusinessCombinationDeferredFinancingCostsExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fa2bc-afeb-7f35-a33b-717cfa83bafb" xlink:to="loc_tln_BusinessCombinationDeferredFinancingCostsExpense_019fb52c-01d1-7cd0-8051-2d4737ab9dd6" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestituresSummaryofPurchasePriceDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AcquisitionsandDivestituresSummaryofPurchasePriceDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestituresSummaryofPurchasePriceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f8e0a-3971-7d6d-a4eb-d4b257b33f00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f8e0a-3971-7d6d-a4eb-d4b257b33f00" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f8e0a-3971-7fed-8a61-1200e43797f8" 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_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f8e0a-3971-7d6d-a4eb-d4b257b33f00" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f8e0a-3971-7fed-8a61-1200e43797f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8e0a-3971-7fed-8a61-1200e43797f8_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_019f8e0a-3971-7fed-8a61-1200e43797f8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8e0a-3971-7fed-8a61-1200e43797f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8e0a-3971-7fb2-90e8-81b4e38fd3c5" 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_019f8e0a-3971-7fed-8a61-1200e43797f8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8e0a-3971-7fb2-90e8-81b4e38fd3c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CornerstoneAcquisitionMember_019f8e0a-3971-7dd0-bf93-6c2ecbe3ff7d" xlink:href="tln-20260630.xsd#tln_CornerstoneAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8e0a-3971-7fb2-90e8-81b4e38fd3c5" xlink:to="loc_tln_CornerstoneAcquisitionMember_019f8e0a-3971-7dd0-bf93-6c2ecbe3ff7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f8e0a-3971-74ff-87cb-6635b633e095" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f8e0a-3971-74ff-87cb-6635b633e095" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f8e0a-3971-7d99-9957-56d761461795" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f8e0a-3971-7d99-9957-56d761461795" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_019f8e0a-3971-7b22-b582-e35e1c73b1ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_019f8e0a-3971-7b22-b582-e35e1c73b1ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f8e0a-3971-7588-8663-fa7f86131c09" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f8e0a-3971-7588-8663-fa7f86131c09" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f8e0a-3971-720f-93fc-150a95ab4860" 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_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f8e0a-3971-720f-93fc-150a95ab4860" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019fad09-474e-7783-8dab-da357b2a2453" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8e0a-3971-7f18-8e2b-eea58bdc0d11" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019fad09-474e-7783-8dab-da357b2a2453" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestituresScheduleofConsiderationPaidandAllocationofPurchasePricetotheFairValueDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AcquisitionsandDivestituresScheduleofConsiderationPaidandAllocationofPurchasePricetotheFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestituresScheduleofConsiderationPaidandAllocationofPurchasePricetotheFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f8dfa-d87c-75ae-ab36-e2e0d7c84763" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f8dfa-d87c-75ae-ab36-e2e0d7c84763" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f8dfa-d87c-7d37-bc51-3b948408faf1" 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_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f8dfa-d87c-75ae-ab36-e2e0d7c84763" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f8dfa-d87c-7d37-bc51-3b948408faf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8dfa-d87c-7d37-bc51-3b948408faf1_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_019f8dfa-d87c-7d37-bc51-3b948408faf1" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8dfa-d87c-7d37-bc51-3b948408faf1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8dfa-d87c-789b-8ff5-c7486b75dbdf" 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_019f8dfa-d87c-7d37-bc51-3b948408faf1" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8dfa-d87c-789b-8ff5-c7486b75dbdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CornerstoneAcquisitionMember_019f8dfa-d87c-7031-bd8c-2da5720ad841" xlink:href="tln-20260630.xsd#tln_CornerstoneAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f8dfa-d87c-789b-8ff5-c7486b75dbdf" xlink:to="loc_tln_CornerstoneAcquisitionMember_019f8dfa-d87c-7031-bd8c-2da5720ad841" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_019f8dfa-d87c-7db9-bb12-eeaa5668e27d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_019f8dfa-d87c-7db9-bb12-eeaa5668e27d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_019f8dfa-d87c-777f-a40f-ed5df416913e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_019f8dfa-d87c-777f-a40f-ed5df416913e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_019f8dfa-d87c-7931-8052-991a3047693f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_019f8dfa-d87c-7931-8052-991a3047693f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_019f8dfa-d87c-727a-b909-5f597eb6fc20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_019f8dfa-d87c-727a-b909-5f597eb6fc20" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019f8dfa-d87c-7d74-bbdd-f7035bc514eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019f8dfa-d87c-7d74-bbdd-f7035bc514eb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_019f8dfa-d87c-70dc-869d-a93877504af2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_019f8dfa-d87c-70dc-869d-a93877504af2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_019f8dfa-d87c-7d42-bd31-23867b9d8879" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_019f8dfa-d87c-7d42-bd31-23867b9d8879" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BusinessCombinationRecognizedLiabilityAssumedDerivativeLiabilitiesCurrent_019f8dfa-d87c-7c38-9ba8-cddd5c1e5768" xlink:href="tln-20260630.xsd#tln_BusinessCombinationRecognizedLiabilityAssumedDerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_tln_BusinessCombinationRecognizedLiabilityAssumedDerivativeLiabilitiesCurrent_019f8dfa-d87c-7c38-9ba8-cddd5c1e5768" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAssetRetirementObligations_019f8dfa-d87c-7479-b13f-ea8190c791e9" xlink:href="tln-20260630.xsd#tln_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_tln_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAssetRetirementObligations_019f8dfa-d87c-7479-b13f-ea8190c791e9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BusinessCombinationRecognizedLiabilityAssumedAcquiredContractLiabilities_019f8dfa-d87c-7dac-ae7e-b8a7936f2c73" xlink:href="tln-20260630.xsd#tln_BusinessCombinationRecognizedLiabilityAssumedAcquiredContractLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_tln_BusinessCombinationRecognizedLiabilityAssumedAcquiredContractLiabilities_019f8dfa-d87c-7dac-ae7e-b8a7936f2c73" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019f8dfa-d87c-7f3a-9ddf-c22d406ad4aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019f8dfa-d87c-7f3a-9ddf-c22d406ad4aa" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BusinessCombinationRecognizedLiabilityAssumedDerivativeLiabilitiesNonCurrent_019f8dfa-d87c-77fc-bc8e-cd8e370c8380" xlink:href="tln-20260630.xsd#tln_BusinessCombinationRecognizedLiabilityAssumedDerivativeLiabilitiesNonCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_tln_BusinessCombinationRecognizedLiabilityAssumedDerivativeLiabilitiesNonCurrent_019f8dfa-d87c-77fc-bc8e-cd8e370c8380" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f8dfa-d87c-745f-9b70-1802b05edd9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f8dfa-d87c-745f-9b70-1802b05edd9c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019f8dfa-d87c-7b70-b4b6-93a30f346fa4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f8dfa-d87c-7950-963a-8c5fc5394a2d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019f8dfa-d87c-7b70-b4b6-93a30f346fa4" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestituresScheduleofRevenuesandEarningsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AcquisitionsandDivestituresScheduleofRevenuesandEarningsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestituresScheduleofRevenuesandEarningsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionLineItems_019f5c50-267f-7917-832f-7b45d2c3edbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionTable_019f5c50-267f-74d7-9710-4ec602873e48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f5c50-267f-7917-832f-7b45d2c3edbd" xlink:to="loc_us-gaap_AssetAcquisitionTable_019f5c50-267f-74d7-9710-4ec602873e48" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f5c50-267f-7226-ab5c-05ba38381cdd" 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_AssetAcquisitionTable_019f5c50-267f-74d7-9710-4ec602873e48" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f5c50-267f-7226-ab5c-05ba38381cdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c50-267f-7226-ab5c-05ba38381cdd_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_019f5c50-267f-7226-ab5c-05ba38381cdd" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c50-267f-7226-ab5c-05ba38381cdd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c50-267f-7997-ad89-02152341c60e" 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_019f5c50-267f-7226-ab5c-05ba38381cdd" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c50-267f-7997-ad89-02152341c60e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CornerstoneAcquisitionMember_019f5c50-a409-7d76-a2b9-a8fed91355ae" xlink:href="tln-20260630.xsd#tln_CornerstoneAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c50-267f-7997-ad89-02152341c60e" xlink:to="loc_tln_CornerstoneAcquisitionMember_019f5c50-a409-7d76-a2b9-a8fed91355ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_019f5c50-267f-7f50-a88d-7f9bbf90ace1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f5c50-267f-7917-832f-7b45d2c3edbd" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_019f5c50-267f-7f50-a88d-7f9bbf90ace1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_019f5c50-267f-76a7-b6fb-ee74a7c665bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f5c50-267f-7917-832f-7b45d2c3edbd" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_019f5c50-267f-76a7-b6fb-ee74a7c665bb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestituresScheduleofUnauditedProFormaFinancialInformationDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AcquisitionsandDivestituresScheduleofUnauditedProFormaFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestituresScheduleofUnauditedProFormaFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionLineItems_019f5c4e-fd57-799a-ab39-3ea76be29713" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionTable_019f5c4e-fd57-7749-9367-6107a6ebfe1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f5c4e-fd57-799a-ab39-3ea76be29713" xlink:to="loc_us-gaap_AssetAcquisitionTable_019f5c4e-fd57-7749-9367-6107a6ebfe1a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f5c4e-fd57-75ef-8d47-ea5905043d78" 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_AssetAcquisitionTable_019f5c4e-fd57-7749-9367-6107a6ebfe1a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f5c4e-fd57-75ef-8d47-ea5905043d78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c4e-fd57-75ef-8d47-ea5905043d78_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_019f5c4e-fd57-75ef-8d47-ea5905043d78" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c4e-fd57-75ef-8d47-ea5905043d78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c4e-fd57-76a3-b052-de0393eb71e2" 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_019f5c4e-fd57-75ef-8d47-ea5905043d78" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c4e-fd57-76a3-b052-de0393eb71e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CornerstoneAcquisitionMember_019f5c4f-93ab-7d85-927c-a7348c2383be" xlink:href="tln-20260630.xsd#tln_CornerstoneAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f5c4e-fd57-76a3-b052-de0393eb71e2" xlink:to="loc_tln_CornerstoneAcquisitionMember_019f5c4f-93ab-7d85-927c-a7348c2383be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_019f5c4e-fd57-7574-9817-3f5de2277607" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f5c4e-fd57-799a-ab39-3ea76be29713" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_019f5c4e-fd57-7574-9817-3f5de2277607" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_019f5c4e-fd57-7507-826a-c8c612422dbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f5c4e-fd57-799a-ab39-3ea76be29713" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_019f5c4e-fd57-7507-826a-c8c612422dbe" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestituresDivestituresNarrativeDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#AcquisitionsandDivestituresDivestituresNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestituresDivestituresNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8e25-227c-7acf-8519-48fd5eb67393" 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_019f8e25-227c-7756-acb5-ff448a8ab9e6" 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_019f8e25-227c-7acf-8519-48fd5eb67393" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f8e25-227c-7756-acb5-ff448a8ab9e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019f8e25-227c-7c48-bde3-407e770d0c6f" 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_019f8e25-227c-7756-acb5-ff448a8ab9e6" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019f8e25-227c-7c48-bde3-407e770d0c6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f8e25-227c-7c48-bde3-407e770d0c6f_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_019f8e25-227c-7c48-bde3-407e770d0c6f" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f8e25-227c-7c48-bde3-407e770d0c6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f8e25-227c-70f7-b62e-077ae907a88b" 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_019f8e25-227c-7c48-bde3-407e770d0c6f" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f8e25-227c-70f7-b62e-077ae907a88b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019f8e25-227c-7d03-b939-091050100438" 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_019f8e25-227c-70f7-b62e-077ae907a88b" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_019f8e25-227c-7d03-b939-091050100438" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019f8e25-227c-7c2e-a1a8-709c72545b93" 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_019f8e25-227c-7756-acb5-ff448a8ab9e6" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019f8e25-227c-7c2e-a1a8-709c72545b93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8e25-227c-7c2e-a1a8-709c72545b93_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_019f8e25-227c-7c2e-a1a8-709c72545b93" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8e25-227c-7c2e-a1a8-709c72545b93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8e25-227c-7c08-b220-d47a271eb6a2" 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_019f8e25-227c-7c2e-a1a8-709c72545b93" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8e25-227c-7c08-b220-d47a271eb6a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_KeystoneGenerationFacilityMember_019f8e25-227c-7c12-aef8-aec3b4185630" xlink:href="tln-20260630.xsd#tln_KeystoneGenerationFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019f8e25-227c-7c08-b220-d47a271eb6a2" xlink:to="loc_tln_KeystoneGenerationFacilityMember_019f8e25-227c-7c12-aef8-aec3b4185630" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019faf6a-6e12-7129-81f1-60f5ff47ee9b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f8e25-227c-7756-acb5-ff448a8ab9e6" xlink:to="loc_srt_StatementScenarioAxis_019faf6a-6e12-7129-81f1-60f5ff47ee9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019faf6a-6e12-7129-81f1-60f5ff47ee9b_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_019faf6a-6e12-7129-81f1-60f5ff47ee9b" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019faf6a-6e12-7129-81f1-60f5ff47ee9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019faf6a-6e12-756b-9c9f-67b1f5f75e4d" 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_019faf6a-6e12-7129-81f1-60f5ff47ee9b" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019faf6a-6e12-756b-9c9f-67b1f5f75e4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019faf6a-8e40-70d4-a2d0-ac1f3a4b83a9" 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_019faf6a-6e12-756b-9c9f-67b1f5f75e4d" xlink:to="loc_srt_ScenarioForecastMember_019faf6a-8e40-70d4-a2d0-ac1f3a4b83a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DisposalGroupIncludingDiscontinuedOperationOwnershipInterestAndAssetsPercentage_019f8e25-227c-73f9-a0fb-39b75db5c001" xlink:href="tln-20260630.xsd#tln_DisposalGroupIncludingDiscontinuedOperationOwnershipInterestAndAssetsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f8e25-227c-7acf-8519-48fd5eb67393" xlink:to="loc_tln_DisposalGroupIncludingDiscontinuedOperationOwnershipInterestAndAssetsPercentage_019f8e25-227c-73f9-a0fb-39b75db5c001" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_019f8e25-227c-7635-a55b-3d80e0132927" 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_019f8e25-227c-7acf-8519-48fd5eb67393" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_019f8e25-227c-7635-a55b-3d80e0132927" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/SegmentsSegmentsandReconciliationDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#SegmentsSegmentsandReconciliationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/SegmentsSegmentsandReconciliationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7cfe-ab25-7f052d0cc244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7cfe-ab25-7f052d0cc244" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e69cb-6548-71d2-a604-5f066c0ba801" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7cfe-ab25-7f052d0cc244" xlink:to="loc_srt_ConsolidationItemsAxis_019e69cb-6548-71d2-a604-5f066c0ba801" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e69cb-6548-71d2-a604-5f066c0ba801_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e69cb-6548-71d2-a604-5f066c0ba801" xlink:to="loc_srt_ConsolidationItemsDomain_019e69cb-6548-71d2-a604-5f066c0ba801_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7933-8263-f3dd558352a9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e69cb-6548-71d2-a604-5f066c0ba801" xlink:to="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7933-8263-f3dd558352a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019e69cb-6548-7470-b0f7-68bccf772e4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7933-8263-f3dd558352a9" xlink:to="loc_us-gaap_OperatingSegmentsMember_019e69cb-6548-7470-b0f7-68bccf772e4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CorporateAndEliminationsMember_019e69cb-6548-78d0-aa53-186fd9f8f04d" xlink:href="tln-20260630.xsd#tln_CorporateAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7933-8263-f3dd558352a9" xlink:to="loc_tln_CorporateAndEliminationsMember_019e69cb-6548-78d0-aa53-186fd9f8f04d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-7e1d-9193-3f44e73f6cad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7cfe-ab25-7f052d0cc244" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-7e1d-9193-3f44e73f6cad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e69cb-6548-7e1d-9193-3f44e73f6cad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-7e1d-9193-3f44e73f6cad" xlink:to="loc_us-gaap_SegmentDomain_019e69cb-6548-7e1d-9193-3f44e73f6cad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e69cb-6548-746d-8926-6765ec740377" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-7e1d-9193-3f44e73f6cad" xlink:to="loc_us-gaap_SegmentDomain_019e69cb-6548-746d-8926-6765ec740377" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PJMSegmentMember_019e69cb-6548-74cf-b398-8a42c3fff524" xlink:href="tln-20260630.xsd#tln_PJMSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e69cb-6548-746d-8926-6765ec740377" xlink:to="loc_tln_PJMSegmentMember_019e69cb-6548-74cf-b398-8a42c3fff524" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllOtherSegmentsMember_019e69cb-6548-76c9-ac62-1b8fb88b0c50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllOtherSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e69cb-6548-746d-8926-6765ec740377" xlink:to="loc_us-gaap_AllOtherSegmentsMember_019e69cb-6548-76c9-ac62-1b8fb88b0c50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e69cb-6548-7a20-882e-cf9eac5af186" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_us-gaap_Revenues_019e69cb-6548-7a20-882e-cf9eac5af186" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperationMaintenanceAndDevelopmentExpense_019e69cb-6548-7df2-91b6-75b5e8e4d2e8" xlink:href="tln-20260630.xsd#tln_OperationMaintenanceAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_tln_OperationMaintenanceAndDevelopmentExpense_019e69cb-6548-7df2-91b6-75b5e8e4d2e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_019e69cb-6548-7ef4-a2e7-db7160a95b20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_us-gaap_InterestAndDebtExpense_019e69cb-6548-7ef4-a2e7-db7160a95b20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019e69cb-6548-7010-a01c-070b3d965745" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019e69cb-6548-7010-a01c-070b3d965745" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_019e69cb-6548-74d4-af54-de0c7cdae75f" xlink:href="tln-20260630.xsd#tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_019e69cb-6548-74d4-af54-de0c7cdae75f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019e69cb-6548-7715-802e-7b2636ae7639" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7cdf-938a-775afab48c82" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019e69cb-6548-7715-802e-7b2636ae7639" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/SegmentsScheduleofAdjustedEBITDAandReconcilingItemsDetails" xlink:type="simple" xlink:href="tln-20260630.xsd#SegmentsScheduleofAdjustedEBITDAandReconcilingItemsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/SegmentsScheduleofAdjustedEBITDAandReconcilingItemsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7fc1-9ac3-e8a78b5c7984" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7340-b1d0-3c7cdf1fdf7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7fc1-9ac3-e8a78b5c7984" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7340-b1d0-3c7cdf1fdf7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e69cb-6548-73e8-8b09-e747f095f3c1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7340-b1d0-3c7cdf1fdf7c" xlink:to="loc_srt_ConsolidationItemsAxis_019e69cb-6548-73e8-8b09-e747f095f3c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e69cb-6548-73e8-8b09-e747f095f3c1_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e69cb-6548-73e8-8b09-e747f095f3c1" xlink:to="loc_srt_ConsolidationItemsDomain_019e69cb-6548-73e8-8b09-e747f095f3c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7716-a15b-84e648376835" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e69cb-6548-73e8-8b09-e747f095f3c1" xlink:to="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7716-a15b-84e648376835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019e69cb-6548-74a8-8ac5-da80655b3ec4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7716-a15b-84e648376835" xlink:to="loc_us-gaap_OperatingSegmentsMember_019e69cb-6548-74a8-8ac5-da80655b3ec4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CorporateAndEliminationsMember_019e69cb-6548-7884-9c72-d11bd6a498af" xlink:href="tln-20260630.xsd#tln_CorporateAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e69cb-6548-7716-a15b-84e648376835" xlink:to="loc_tln_CorporateAndEliminationsMember_019e69cb-6548-7884-9c72-d11bd6a498af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-79d8-b05a-6ed031e95e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e69cb-6548-7340-b1d0-3c7cdf1fdf7c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-79d8-b05a-6ed031e95e4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e69cb-6548-79d8-b05a-6ed031e95e4f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-79d8-b05a-6ed031e95e4f" xlink:to="loc_us-gaap_SegmentDomain_019e69cb-6548-79d8-b05a-6ed031e95e4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e69cb-6548-777b-9c19-5b70f5418e17" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e69cb-6548-79d8-b05a-6ed031e95e4f" xlink:to="loc_us-gaap_SegmentDomain_019e69cb-6548-777b-9c19-5b70f5418e17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PJMSegmentMember_019e69cb-6548-7aca-b5f5-60c6869a48e0" xlink:href="tln-20260630.xsd#tln_PJMSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e69cb-6548-777b-9c19-5b70f5418e17" xlink:to="loc_tln_PJMSegmentMember_019e69cb-6548-7aca-b5f5-60c6869a48e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllOtherSegmentsMember_019e69cb-6548-7fa7-9139-d46c7d27301f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllOtherSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e69cb-6548-777b-9c19-5b70f5418e17" xlink:to="loc_us-gaap_AllOtherSegmentsMember_019e69cb-6548-7fa7-9139-d46c7d27301f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedEBITDAAbstract_019e69cb-6548-7398-a129-9de9eac798be" xlink:href="tln-20260630.xsd#tln_AdjustedEBITDAAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7fc1-9ac3-e8a78b5c7984" xlink:to="loc_tln_AdjustedEBITDAAbstract_019e69cb-6548-7398-a129-9de9eac798be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_019e69cb-6548-72f7-b858-de2f439e334e" xlink:href="tln-20260630.xsd#tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_AdjustedEBITDAAbstract_019e69cb-6548-7398-a129-9de9eac798be" xlink:to="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_019e69cb-6548-72f7-b858-de2f439e334e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:href="tln-20260630.xsd#tln_ReconcilingItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e69cb-6548-7fc1-9ac3-e8a78b5c7984" xlink:to="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_019e69cb-6548-7d38-b80f-30d7086f6636" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_us-gaap_InterestAndDebtExpense_019e69cb-6548-7d38-b80f-30d7086f6636" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DepreciationDepletionAndAmortizationAdjusted_019e69cb-6548-7727-a26c-ee162dca0a34" xlink:href="tln-20260630.xsd#tln_DepreciationDepletionAndAmortizationAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_tln_DepreciationDepletionAndAmortizationAdjusted_019e69cb-6548-7727-a26c-ee162dca0a34" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfNuclearFuelLease_019e69cb-6548-7107-be47-ee0d9f589fed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfNuclearFuelLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_us-gaap_AmortizationOfNuclearFuelLease_019e69cb-6548-7107-be47-ee0d9f589fed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_019e69cb-6548-72ba-90be-23817746d36c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_019e69cb-6548-72ba-90be-23817746d36c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_019e69cb-6548-7710-aedd-1f4076ffdded" xlink:href="tln-20260630.xsd#tln_GainLossOnNuclearDecommissioningTrustFundsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_019e69cb-6548-7710-aedd-1f4076ffdded" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_019e69cb-6548-7d54-baed-1b6baf87b0cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_019e69cb-6548-7d54-baed-1b6baf87b0cc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AcquisitionAndDivestitureActivities_019e69cb-6548-7003-8118-978b7a226b25" xlink:href="tln-20260630.xsd#tln_AcquisitionAndDivestitureActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_tln_AcquisitionAndDivestitureActivities_019e69cb-6548-7003-8118-978b7a226b25" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonrecurringIncomeExpense_019e69cb-6548-7b6d-b582-6aabbe4ff17d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonrecurringIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_us-gaap_OtherNonrecurringIncomeExpense_019e69cb-6548-7b6d-b582-6aabbe4ff17d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e69cb-6548-7131-9c45-45d5c087dbc0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_019e69cb-6548-7f24-a04f-2b0cf278b47c" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e69cb-6548-7131-9c45-45d5c087dbc0" xlink:type="arc" order="9"/>
  </link:definitionLink>
</link:linkbase>
