Delfont was born in Tokmak, Berdyansky Uyezd, Taurida Governorate, Russian Empire (now Ukraine), the second son of Isaac and Olga Winogradsky, a Jewish family.

[3][4] He acquired the London Casino and converted the London Hippodrome into the Talk of the Town nightclub, bringing in entertainers such as Lena Horne, Shirley Bassey, Frank Sinatra, Eartha Kitt, Judy Garland, The Ink Spots, Sophie Tucker, Barbra Streisand, Sammy Davis Jr. and Laurel & Hardy[3][6][4] and also secured the exclusive rights from Paul Derval to stage the Folies Bergère for the first time outside Paris.

He also teamed up with former rival Val Parnell to acquire a lease on the Prince of Wales Theatre and stage shows at the London Palladium.

In 1969 he became chief executive of Associated British Picture Corporation after it was acquired by EMI and was a board member for around 30 entertainment entities, including the Blackpool Tower Company.

[7] As head of EMI's leisure division, Delfont oversaw film production, including The Go-Between (1971), Murder on the Orient Express (1974), Death on the Nile and The Deer Hunter (both 1978).

[9][4] In that role he withdrew funding for the film Life of Brian in 1978 at the last moment owing to worries over the religious implications of the screenplay.

[4][16] In the 2018 film Stan & Ollie, which recounts the 1953 tour of the United Kingdom by Laurel & Hardy, he is portrayed by Rufus Jones.