The Metropolitan Borough of Westminster was a metropolitan borough under the County of London from 1899 to 1965, when it was amalgamated into the London Borough of Westminster along with the Metropolitan Borough of Paddington and the Metropolitan Borough of St Marylebone.

It consisted of the part of the London Borough of Westminster south of Oxford Street and Bayswater Road. It included Soho, Mayfair, St James's, The Strand, Westminster, Pimlico, Belgravia, and Hyde Park.

It was formed from various parishes, including the old borough of Westminster, and St George's Hanover Square and St Martin-in-the-Fields.