<SEC-DOCUMENT>0001209191-21-052355.txt : 20210818
<SEC-HEADER>0001209191-21-052355.hdr.sgml : 20210818
<ACCEPTANCE-DATETIME>20210818183402
ACCESSION NUMBER:		0001209191-21-052355
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210816
FILED AS OF DATE:		20210818
DATE AS OF CHANGE:		20210818

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Day David
		CENTRAL INDEX KEY:			0001523288

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36384
		FILM NUMBER:		211187788

	MAIL ADDRESS:	
		STREET 1:		21700 OXNARD STREET
		STREET 2:		SUITE 1600
		CITY:			WOODLAND HILLS
		STATE:			CA
		ZIP:			91367

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MAGNITE, INC.
		CENTRAL INDEX KEY:			0001595974
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER PROGRAMMING, DATA PROCESSING, ETC. [7370]
		IRS NUMBER:				208881738
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		12181 BLUFF CREEK DRIVE, 4TH FLOOR
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90094
		BUSINESS PHONE:		310-207-0272

	MAIL ADDRESS:	
		STREET 1:		12181 BLUFF CREEK DRIVE, 4TH FLOOR
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90094

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RUBICON PROJECT, INC.
		DATE OF NAME CHANGE:	20140106
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-08-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001595974</issuerCik>
        <issuerName>MAGNITE, INC.</issuerName>
        <issuerTradingSymbol>MGNI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001523288</rptOwnerCik>
            <rptOwnerName>Day David</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MAGNITE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>6080 CENTER DRIVE, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90045</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5177</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.82</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>268349</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents the non-discretionary sale of shares on behalf of the Reporting Person pursuant to an arrangement mandated by the Issuer to cover the tax withholding obligations associated with the vesting of restricted stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Aaron Saltz, attorney-in-fact</signatureName>
        <signatureDate>2021-08-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
