Born in Croydon, London, Dean started his career in showbusiness in London as a West End stage actor, and then later became a theatrical producer. He later moved into the film industry and in the early 1930s founded Associated Talking Pictures, which later became Ealing Studios. He publicised and worked alongside Gracie Fields and George Formby, among other entertainers. When the war started he left the film industry and became the head of ENSA, the government-sponsored body responsible for bringing live performances to the armed services. He was awarded the CBE for his work with ENSA, which he described in a book called The Theatre at War.
His wives included Lady Mercy Greville and Esther Van Gruisen. From August 1934 until 1939 he was married to British stage and film actress, Victoria Hopper. Dean had a relationship with one of his theatre and film stars Meggie Albanesi and after her early death in 1923 continued to be obsessed with her.
His son Winton (1916-2013) became a noted musicologist.
Dean died in Westminster, London from a heart attack at the age of 89.