He was soon cast in his first British movie, playing a murderous actor in Train of Events (1949). Critic C. A. Lejeune praised his work in the London Observer commenting that he "adds good cheekbones to a quick intelligence and is likely to become a cult, I fear." The Scotsman said "he should be regarded as one of the most hopeful recruits to the British screen."
However, he was then cast as an Australian soldier in A Town Like Alice (1956), which became the third most popular film at the British box office in 1956 and won Finch a BAFTA for Best Actor. He followed it with The Battle of the River Plate (1956), playing Captain Hans Langsdorff. This was also successful financially and British exhibitors voted Finch the seventh most popular British star at the box office for 1956.
Finch's film roles increased in size and prestige through the early 1950s. For Walt Disney he played the Sheriff of Nottingham in The Story of Robin Hood and His Merrie Men (1952). He was given two good roles in films from Alexander Korda: as Richard D'Oyly Carte in The Story of Gilbert and Sullivan (1953), and as a priest in The Heart of the Matter (1953), from the Graham Greene novel.
Finch co-wrote and directed an award-winning short film, The Day (1960) and announced plans to direct a feature but it did not eventuate. He won his third BAFTA for Best Actor for No Love for Johnnie (1961), although like Oscar Wilde, the film lost money. He was originally chosen to play Julius Caesar in Cleopatra (1963) and filmed scenes in London, but when the film was postponed he withdrew; the role was recast with Rex Harrison.