| Cover | Apr. 21, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Apr. 21, 2022 |
| Entity File Number | 001-40379 |
| Entity Registrant Name | FIVE STAR BANCORP |
| Entity Central Index Key | 0001275168 |
| Entity Tax Identification Number | 75-3100966 |
| Entity Incorporation, State or Country Code | CA |
| Entity Address, Address Line One | 3100 Zinfandel Drive |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | Rancho Cordova |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95670 |
| City Area Code | (916) |
| Local Phone Number | 626-5000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, no par value per share |
| Trading Symbol | FSBC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
