<SEC-DOCUMENT>0001841671-25-000003.txt : 20251124
<SEC-HEADER>0001841671-25-000003.hdr.sgml : 20251124
<ACCEPTANCE-DATETIME>20251124171032
ACCESSION NUMBER:		0001841671-25-000003
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20251120
FILED AS OF DATE:		20251124
DATE AS OF CHANGE:		20251124

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Blackie James
		CENTRAL INDEX KEY:			0001841671
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39965
		FILM NUMBER:		251514127

	MAIL ADDRESS:	
		STREET 1:		930 N WETHERLY DR #304
		CITY:			WEST HOLLYWOOD
		STATE:			CA
		ZIP:			90069

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ON24 INC.
		CENTRAL INDEX KEY:			0001110611
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		ORGANIZATION NAME:           	06 Technology
		EIN:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		301 HOWARD STREET, SUITE 1100
		CITY:			SAN FRANCISCO
		STATE:			CA
		BUSINESS PHONE:		(415) 369-8000

	MAIL ADDRESS:	
		STREET 1:		301 HOWARD STREET, SUITE 1100
		CITY:			SAN FRANCISCO
		STATE:			CA

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ON24 INC
		DATE OF NAME CHANGE:	20000329
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primarydocument.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-11-20</periodOfReport>

    <notSubjectToSection16>false</notSubjectToSection16>

    <issuer>
        <issuerCik>0001110611</issuerCik>
        <issuerName>ON24 INC.</issuerName>
        <issuerTradingSymbol>ONTF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001841671</rptOwnerCik>
            <rptOwnerName>Blackie James</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ON24, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>301 HOWARD STREET, SUITE 1100</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Chief Revenue Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>true</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-11-20</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4659.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.2978</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>501411.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The transactions reported in this Form 4 was effected pursuant to a Rule 10B5-1 trading plan adopted by the reporting person on August 29, 2024.</footnote>
        <footnote id="F2">Represents the number of shares sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units.</footnote>
        <footnote id="F3">The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $5.20 to $ 5.37 inclusive. The reporting person undertakes to provide to Issuer, any security holder of Issuer, or the staff of the Security and Exchange Commission, upon request, full information regarding the number of shares sold in each separate price within the ranges set forth in footnote (3) to this Form 4.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Blackie James by Charles Rogerson, as Attorney-in-Fact</signatureName>
        <signatureDate>2025-11-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
