| Jurisdiction: | Diocese |
| San Sebastián | |
| Latin: | Dioecesis Sancti Sebastiani |
| Local: | Diócesis de San Sebastián (es) Donostiako elizbarrutia (eu) |
| Country: | Spain |
| Metropolitan: | Pamplona y Tudela |
| Province: | Pamplona y Tudela |
| Rite: | Latin Rite |
| Established: | 2 November 1949 |
| Cathedral: | Cathedral of the Good Shepherd in San Sebastián |
| Area Km2: | 1,977 |
| Population: | 684,416 |
| Population As Of: | 2004 |
| Catholics: | 621,988 |
| Catholics Percent: | 90.9 |
| Metro Archbishop: | Florencio Roselló Avellanas |
| Website: | Website of the Diocese |
The Diocese of San Sebastián (Latin: Sancti Sebastiani) is a Latin Church diocese of the Catholic Church located in the city of San Sebastián in the ecclesiastical province of Pamplona y Tudela in Spain.