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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-05-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001437107</issuerCik>
        <issuerName>Discovery, Inc.</issuerName>
        <issuerTradingSymbol>DISCA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001753932</rptOwnerCik>
            <rptOwnerName>Faricy Peter</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>8403 COLESVILLE ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SILVER SPRING</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20910</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO, Global Direct to Consumer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Series A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-05-28</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>35900</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>27.91</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>182367</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price reported represents the weighted average purchase price of shares of Series A common stock purchased in multiple transactions at prices ranging from $27.69 to $28.00 per share. The reporting person will provide to the Issuer, any security holder of the Issuer, or the SEC staff, upon request, information regarding the number of shares purchased at each price within the range.</footnote>
    </footnotes>

    <remarks>The trading symbols for the Issuer's Series A, Series B and Series C common stock are, respectively, DISCA, DISCB and DISCK.</remarks>

    <ownerSignature>
        <signatureName>Stephanie D. Marks, by power of attorney</signatureName>
        <signatureDate>2019-05-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
