During his war service Finch was given leave to act in radio, theatre and film. He appeared in a number of propaganda shorts, including Another Threshold (1942), These Stars Are Mine (1943), While There is Still Time (1943) and South West Pacific (1943), the latter for Ken G. Hall. He also appeared in two of the few Australian feature films made during the war, The Rats of Tobruk (1944) and the less distinguished Red Sky at Morning (1944).
Finch returned to Australia to make The Shiralee (1957), one of his favourite parts, and the tenth most popular movie at the British box office that year. He followed it with another Australian story, the bushranger tale Robbery Under Arms (1957), which did less well. However exhibitors still voted Finch the third most popular British star of 1957, and the fifth most popular overall, regardless of nationality.
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 was married three times. In 1943, he married Romanian-born French ballerina Tamara Tchinarova; they worked together on a number of films. They had a daughter, Anita, born in 1950. They divorced in 1959, after she discovered his affair with actress Vivien Leigh in California. He then married South African-born actress Yolande Turner (née Yolande Eileen Turnbull); they had two children together, Samantha and Charles Peter. During their marriage, Finch had an affair with the singer Shirley Bassey. Bassey had a daughter, also named Samantha, born in 1963; Bassey's husband at the time, the openly gay film producer Kenneth Hume, believed that Finch was her biological father. Finch and Turner divorced in 1965. In 1972 Finch married Mavis "Eletha" Barrett, who was known as Eletha Finch. They had a daughter together, Diana.