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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-12-31</periodOfReport>

    <issuer>
        <issuerCik>0001760965</issuerCik>
        <issuerName>Kontoor Brands, Inc.</issuerName>
        <issuerTradingSymbol>KTB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001306837</rptOwnerCik>
            <rptOwnerName>Carucci Richard</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>400 N. ELM STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENSBORO</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>27401</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock-d</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>519.687</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.89</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>519.687</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3638.1633</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents phantom stock units (&quot;PSUs&quot;) accrued under the Kontoor Brands Deferred Savings Plan For Non-Employee Directors (&quot;Plan&quot;), to be settled 100% in cash upon the reporting person's retirement. The number of PSUs acquired equals the amount of Directors' fees deferred by the reporting person divided by the fair market value (average of the high and low selling prices) per share on the date of deferral. The number of PSUs beneficially owned may vary over time due to deemed reinvestment of dividends.</footnote>
        <footnote id="F2">1 for 1.</footnote>
        <footnote id="F3">There is no date that should appear in these columns. These columns are not applicable to this particular filing.</footnote>
        <footnote id="F4">Each PSU was acquired at the election of the Director by deferring $40.8900 of fees per PSU.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Laurel Krueger for Richard T. Carucci (Pursuant to Signing Authority on File)</signatureName>
        <signatureDate>2021-01-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
