Page 1

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ Commission File Number 001-39965 ON24 , INC . ( Exact name of Registrant as specified in its Charter ) Delaware ( State or other jurisdiction of incorporation or organization ) Large accelerated filer Non - accelerated filer 50 Beale Street , 8th Floor , San Francisco , California ( Address of principal executive offices ) Registrant's telephone number , including area code : ( 415 ) 369-8000 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) . 94-3292599 ( I.R.S. Employer Identification No. ) Title of each class Common Stock , par value $ 0.0001 per share Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by check mark if the Registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . YES □ NO Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Act . YES □ NO > Indicate by check mark whether the Registrant : ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the Registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . YES □ NO " ONTF 94105 ( Zip Code ) Name of each exchange on which registered New York Stock Exchange Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the Registrant was required to submit such files ) . YES " NO ☐ Indicate by check mark whether the Registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer " , " accelerated filer " , " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act : No items are incorporated by reference into this Annual Report on Form 10 - K Accelerated filer Smaller reporting company Emerging growth company If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7 ( a ) ( 2 ) ( B ) of the Securities Act . □ Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . □ Indicate by check mark whether the Registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . YES □ NO > The registrant's common stock was not publicly traded as of the last business day of the registrant's most recently completed second fiscal quarter . The number of shares of Registrant's Common Stock outstanding as of March 23 , 2021 was 46,313,063 shares . DOCUMENTS INCORPORATED BY REFERENCE