Fabrizi was born to Italian parents in Holborn, London, England, in 1924, his mother's maiden name being Pisani. His father was a Vicomte (Italian: visconte), a title that Mario inherited on his father's death in 1959. He married Katherine Boyne of Leeds on 28 May 1960. They had a son, Anthony, in 1961. On 5 April 1963 Fabrizi died of a stress-related illness at his home in Neasden, London; his wife and son survived him. A week before his death, he had announced that he was leaving show business. His son Anthony is now a businessman based in the City of London.