| Jurisdiction: | Diocese |
| Wanxian | |
| Local: | Chinese: 天主教萬縣教區 Chinese: 天主教万县教区 |
| Latin: | Dioecesis Uanscienensis |
| Country: | China |
| Province: | Chongqing |
| Metropolitan: | Chongqing |
| Established: | August 2, 1929 |
| Denomination: | Catholic |
| Sui Iuris Church: | Latin Church |
| Rite: | Roman Rite |
| Cathedral: | Cathedral of the Immaculate Conception, Wanzhou |
| Area Km2: | 20,000 |
| Population: | 1,700,000 |
| Population As Of: | 2009 |
| Catholics: | 60,000 |
| Catholics Percent: | 3.5 |
| Bishop: | Paul He Zeqing |
| Metro Archbishop: | Sede vacante |
The Roman Catholic Diocese of Wanxian (formerly spelled Wanhsien; Latin: Dioecesis Uanscienensis; Chinese: t=天主教萬縣教區), also known as Diocese of Wanzhou, is a Latin Catholic diocese located in Wanzhou District (formerly Wanxian), Chongqing in the ecclesiastical province of Chongqing, in the easternmost part of western China. It was established on August 2, 1929 as the Apostolic Vicariate of Wanhsien for the Mission of Sichuan (Szechwan).
The Diocese of Wanxian covers Wanzhou District (French: Ouan-hien) and eight counties in the mountainous area of northern Chongqing, namely, Chengkou, Fengjie, Kaixian, Liangping, Wushan, Wuxi, Yunyang and Zhongxian,[1] totaling approximately 20,000 square kilometers. It is bordered by the Diocese of Shunqing to the west, Diocese of Shinan to the east, Apostolic Prefecture of Xing'anfu to the north, and Archdiocese of Chongqing to the south and southwest.