The Diocese of Southwark is one of the 42 dioceses of the Church of England, part of the worldwide Anglican Communion. The diocese forms part of the Province of Canterbury in England. It was created on 1 May 1905 from part of the ancient Diocese of Rochester that was served by a suffragan bishop of Southwark (1891–1905). Before 1877 most of the area was part of the Diocese of Winchester, some being part of the Diocese of London.

The Bishop of Southwark is the ordinary of the Church of England Diocese of Southwark in the Province of Canterbury.