Islington was a civil parish and metropolitan borough in London, England. It was an ancient parish within the county of Middlesex, and formed part of The Metropolis from 1855. The parish was transferred to the County of London in 1889 and became a metropolitan borough in 1900. It was amalgamated with the Metropolitan Borough of Finsbury to form the London Borough of Islington in Greater London in 1965.

The Metropolitan Borough of Finsbury was a metropolitan borough within the County of London from 1900 to 1965, when it was amalgamated with the Metropolitan Borough of Islington to form the London Borough of Islington.