<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-12-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000109177</issuerCik>
        <issuerName>Spectrum Brands Holdings, Inc.</issuerName>
        <issuerTradingSymbol>SPB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001586485</rptOwnerCik>
            <rptOwnerName>Karpel Daniel L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SPECTRUM BRANDS HOLDINGS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3001 DEMING WAY</rptOwnerStreet2>
            <rptOwnerCity>MIDDLETON</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>53562</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Corporate Controller &amp; CAO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-12-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>287</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>99.97</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1633</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the disposition or withholding of shares of common stock to the Issuer to satisfy the reporting person's tax liability resulting from the vesting of restricted stock units.</footnote>
        <footnote id="F2">On December 22, 2020 the Reporting Person was awarded 1,920 time based restricted stock units which are settled in shares of common stock of the Issuer and which are scheduled to vest one-third on December 6, 2021, one-third on December 5, 2022, and one-third on December 4, 2023 if the Reporting Person is an employee of the Issuer on such dates. As of December 6, 2021, 640 restricted stock units have vested and 1,280 restricted stock units remain unvested.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Rich Bretwisch, Attorney-in-fact for Daniel L. Karpel</signatureName>
        <signatureDate>2021-12-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2021-12-06
0
0000109177
Spectrum Brands Holdings, Inc.
SPB
0001586485
Karpel Daniel L
C/O SPECTRUM BRANDS HOLDINGS, INC.
3001 DEMING WAY
MIDDLETON
WI
53562
0
1
0
0
VP, Corporate Controller & CAO
Common Stock
2021-12-06
4
F
0
287
99.97
D
1633
D
Represents the disposition or withholding of shares of common stock to the Issuer to satisfy the reporting person's tax liability resulting from the vesting of restricted stock units.
On December 22, 2020 the Reporting Person was awarded 1,920 time based restricted stock units which are settled in shares of common stock of the Issuer and which are scheduled to vest one-third on December 6, 2021, one-third on December 5, 2022, and one-third on December 4, 2023 if the Reporting Person is an employee of the Issuer on such dates. As of December 6, 2021, 640 restricted stock units have vested and 1,280 restricted stock units remain unvested.
/s/ Rich Bretwisch, Attorney-in-fact for Daniel L. Karpel
2021-12-08