The diocese forms part of the Province of Canterbury in England.

It was created on 1 May 1905[3] from part of the ancient Diocese of Rochester that was served by a suffragan bishop of Southwark (1891–1905).

Since the creation of the diocese's episcopal area scheme in 1991 (which before then had been operating informally for the previous five years),[5] the diocese is divided into three episcopal areas, each of which is overseen by an area bishop and contains two archdeaconries:[6] In other ecclesiastical use, although having lost religious orders in the English Reformation, the diocese has the London home of the Archbishop of Canterbury and records centre of the Church of England in the diocese, Lambeth Palace.

Since 1994 the Bishop of Fulham (currently Jonathan Baker, since 2013) has provided 'alternative episcopal oversight' in the diocese (along with those of London and Rochester) to those parishes which reject the ordination of women to the priesthood.

Baker is licensed as an honorary assistant bishop in Southwark diocese in order to facilitate his ministry there.