| Jurisdiction: | Diocese |
| Basel | |
| Latin: | Diœcesis Basileensis |
| Local: | Bistum Basel |
| Coat: | Wappen Bistum Basel.png |
| Country: |  Switzerland |
| Territory: | Aargau, Basel-Landschaft, Basel-Stadt, Bern, Jura, Lucerne, Schaffhausen, Solothurn, Thurgau, and Zug |
| Metropolitan: | Immediately Subject to the Holy See |
| Area Km2: | 12,585 |
| Area Sqmi: | 4,860 |
| Population: | 3,462,119 |
| Population As Of: | 2022 |
| Catholics: | 1,010,839 |
| Catholics Percent: | 29.2 |
| Parishes: | 483 |
| Denomination: | Catholic |
| Sui Iuris Church: | Latin Church |
| Rite: | Roman Rite |
| Established: | 740 (As Diocese of Basel) 7 September 1888 (As Diocese of Basel e Lugano) 8 March 1971 (As Diocese of Basel) |
| Cathedral: | St. Ursus Cathedral, Solothurn |
| Priests: | 675 |
| Bishop: | Felix Gmür |
| Bishop Title: | Bishop |
| Suffragan: | for one --> |
| Archdeacon: | for one--> |
| Emeritus Bishops: | Hansjörg Vogel Denis Theurillat Martin Gächter |
| Map: | Bistuemer CH 2006 Basel.svg |
| Map Size: | 250px |
The Diocese of Basel (German: Bistum Basel; Latin: Diœcesis Basileensis) is a Latin Catholic diocese in Switzerland.
Historically, the bishops of Basel were also secular rulers of the Prince-Bishopric of Basel (German: Fürstbistum Basel).
The bishop of Basel has not resided in the city of Basel since 1528. Solothurn is the seat of the Bishop of Basel.
Today the diocese of Basel includes the Swiss cantons of Aargau, Basel-Landschaft, Basel-Stadt, Bern, Jura, Lucerne, Schaffhausen, Solothurn, Thurgau, and Zug.
See also: List of Bishops of Basel.