| Cover | Jan. 17, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 17, 2023 |
| Entity Registrant Name | Roblox Corporation |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39763 |
| Entity Tax Identification Number | 20-0991664 |
| Entity Address, Address Line One | 970 Park Place |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock, $0.0001 par value |
| Trading Symbol | RBLX |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001315098 |
