Ornadel first gained prominence as the musical director for many West End shows in the 1950s, including My Fair Lady, Call Me Madam, Kiss Me Kate, Paint Your Wagon, Pal Joey, Wonderful Town, and Kismet.
He was also resident musical director of the London Palladium and conducted the orchestra for Sunday Night at the London Palladium, which was broadcast on ITV from 1955 to 1967.
Pickwick, an adaptation of Charles Dickens' The Pickwick Papers, first played London and transferred to Broadway in 1965, where it ran for 56 performances. The show, which featured lyrics by Leslie Bricusse, yielded a hit song, "If I Ruled the World."
Ornadel wrote numerous other musicals during his multi-faceted career, including Starmaker, Great Expectations, and Treasure Island. He was also a composer and music director for many films and television series, including Subterfuge, Edward the Seventh, and the 1974 TV remake of Brief Encounter, with Sophia Loren and Richard Burton.