The London Borough of Southwark is a London borough in south east London, England. It is directly south of the River Thames and the City of London, and forms part of Inner London.

Southwark got its name in the 9th century but was first settled in the Roman period. The London Borough of Southwark was formed in 1965 from the former area of the Metropolitan Borough of Southwark, the Metropolitan Borough of Camberwell, and the Metropolitan Borough of Bermondsey.

The borough borders the City of London and the London Borough of Tower Hamlets to the north (the River Thames forming the boundary), the London Borough of Lambeth to the west and the London Borough of Lewisham to the east. To the south are the London Borough of Bromley and the London Borough of Croydon.

Tower Bridge, the Millennium Bridge, and London Bridge are within the borough. The skyscraper Shard London Bridge, under construction, will be the tallest building in the EU when completed. The South Bank Centre arts complex, including the National Theatre and Royal Festival Hall are within the borough, as is Shakespeare's Globe Theatre. Borough Market near London Bridge is probably London's most famous food market.