Born in the London suburb of Chingford to Australian parents, Ralph Smart carved out an early career as a screenwriter, working on documentaries, comedies, short films, and features in England during the 1930s and early 1940s. The first known film on which his name appears as writer is The Woodpigeon Patrol (1930).
Smart is believed to have arrived in Australia sometime around 1942-1943, in order to make a number of war documentaries in Papua New Guinea and the Torres Strait. One such film is Island Target (1945). In 1943, he also made a brief appearance as an actor in Ken Hall's documentary South West Pacific. Three years later, he produced Ealing Studios' international hit feature film The Overlanders (1946). He returned to England some time after making Bush Christmas (1947) and enjoyed some celebrity there as a director, before coming back to Australia in 1949 to work on the script of the film Eureka Stockade (1949). In 1950, he directed the film Bitter Springs, starring Chips Rafferty: the pair had previously worked together on Bush Christmas.
Smart was back in England by the mid-1950s, contributing as writer, director, and/or producer to such early television series as The Adventures of Robin Hood, The Adventures of Sir Lancelot, The Buccaneers, William Tell, The Invisible Man, and Danger Man. He returned to Australia in 1966 to produce the television series Riptide. This show was filmed on location in Bowen, Queensland, where Smart went to live in the late 1970s. In 1995, the Bowen Writers' Group staged a retrospective of his work at the Summergarden Theatre.