Exhibit 32.1

Certification Pursuant to Section 906

of the Sarbanes-Oxley Act of 2002

In connection with the Quarterly Report on Form 10-Q of Direct Digital Holdings, Inc. (the “Company”) for the period ended June 30, 2022, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Mark Walker, Chief Executive Officer of the Company, hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:


The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and


The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.


August 15, 2022

/s/ Mark Walker

Mark Walker,

Chairman and Chief Executive Officer

(Principal Executive Officer)