| Document and Entity Information | Feb. 21, 2024 |
| Cover [Abstract] | |
| Entity Registrant Name | Blue Owl Capital Corp III |
| Amendment Flag | false |
| Entity Central Index Key | 0001807427 |
| Document Type | 8-K |
| Document Period End Date | Feb. 21, 2024 |
| Entity Incorporation State Country Code | MD |
| Entity File Number | 814-01345 |
| Entity Tax Identification Number | 84-4493477 |
| Entity Address, Address Line One | 399 Park Avenue |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10022 |
| City Area Code | (212) |
| Local Phone Number | 419-3000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.01 per share |
| Trading Symbol | OBDE |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
