The Metropolitan Borough of Islington was a metropolitan borough within the County of London from 1899 to 1965, when it was amalgamated with the Metropolitan Borough of Finsbury to form the London Borough of Islington.

It included the districts of Pentonville, Islington, Barnsbury, Lower Holloway , Holloway, Tufnell Park, Upper Holloway , Highbury, and Canonbury. The neighbouring boroughs were Finsbury, Hackney, Stoke Newington, Shoreditch, St Pancras.