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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-05-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000105319</issuerCik>
        <issuerName>WW INTERNATIONAL, INC.</issuerName>
        <issuerTradingSymbol>WW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001242894</rptOwnerCik>
            <rptOwnerName>COLOSI MICHAEL F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>675 AVENUE OF THE AMERICAS, 6TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10010</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>General Counsel and Secretary</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <value>Common Stock</value>
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            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
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                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
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                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
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                <footnoteId id="F1"/>
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            <transactionDate>
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            </transactionTimeliness>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2020-05-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2020-05-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2669</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                    <value>D</value>
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                <value>2020-05-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2021-05-15</value>
            </expirationDate>
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                </underlyingSecurityTitle>
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                <footnoteId id="F2"/>
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                <footnoteId id="F1"/>
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                    <value>D</value>
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                <value>2020-05-15</value>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                    <value>8882</value>
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    <footnotes>
        <footnote id="F1">Each restricted stock unit (&quot;RSU&quot;) represents a contingent right to receive one share of common stock.</footnote>
        <footnote id="F2">On May 15, 2017, this award was granted as 7,996 performance stock units (&quot;PSUs&quot;) that had both time- and performance-vesting criteria. The performance-vesting criteria would be satisfied if the Company achieved certain objectives established for each of fiscal 2017, fiscal 2018 and fiscal 2019, as applicable. In February 2018 and 2019, the Compensation and Benefits Committee of the Company's Board of Directors certified that the performance criteria established in connection with the third of the award relating to fiscal 2017 and fiscal 2018, respectively, had been satisfied at the &quot;maximum&quot; level of achievement of 166.67%. Accordingly, those parts of the award converted from PSUs to RSUs. The time-vesting criteria for such RSUs was satisfied on May 15, 2020. The performance-vesting criteria for the fiscal 2019 performance year was not satisfied and therefore had a 0% level of achievement.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Roxanne Tingir, as Attorney-in-Fact for Michael F. Colosi</signatureName>
        <signatureDate>2020-05-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
