Cover Page - USD ($) $ in Billions	12 Months Ended
Cover Page - USD ($) $ in Billions	Dec. 31, 2025	Jan. 30, 2026	Jun. 30, 2025
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-04321
Entity Registrant Name	Roblox Corporation
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	20-0991664
Entity Address, Address Line One	3150 South Delaware Street
Entity Address, City or Town	San Mateo
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94403
City Area Code	888
Local Phone Number	858-2569
Title of 12(b) Security	Class A common stock, par value of $0.0001 per share
Trading Symbol	RBLX
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 65.5
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement relating to its 2026 annual meeting of shareholders (the “2026 Proxy Statement”) are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. The 2026 Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Entity Central Index Key	0001315098
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		661,635,583
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		47,070,464