Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Oct. 11, 2024	Jun. 30, 2023
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Document Transition Report	false
Entity File Number	001-41261
Entity Registrant Name	DIRECT DIGITAL HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	87-2306185
Entity Address, Address Line One	1177 West Loop South
Entity Address, Adress Line Two	Suite 1310
Entity Address, City or Town	Houston
Entity Address State Or Province	TX
Entity Address, Postal Zip Code	77027
City Area Code	832
Local Phone Number	402-1051
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	DRCT
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	No
Entity Interactive Data Current	No
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	true
Document Financial Statement Restatement Recovery Analysis [Flag]	true
Entity Shell Company	false
Entity Public Float				$ 8.3
Auditor Name	BDO USA, P.C.	Marcum LLP
Auditor Firm ID	243	688
Auditor Location	New York, New York	Houston, Texas
Entity Central Index Key	0001880613
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Class A
Entity Common Stock, Shares Outstanding			3,795,199
Common Class B
Entity Common Stock, Shares Outstanding			10,868,000