Randolph Churchill was born on 28 May 1911, only son of Sir Winston Churchill and of Clementine Spencer-Churchill. He was educated at Eton and Christ Church College, University of Oxford, though left Oxford without taking his degree in order to go into journalism. In 1939 he married 1st, Pamela B. Digby (the marriage was dissolved in 1946), daughter of 11th Baron Digby, having one son, Winston; then 2nd, in 1948, June (the marriage was dissolved in 1961), only daughter of Colonel Rex Osborne; they had one daughter, Arabella. In c. 1963, Randolph met and fell in love with a neighbour, Natalie Bevan; their relationship lasted until his death.

Following his father into politics (but without consulting him), Randolph contested the Wavertree Division of Liverpool in February 1935 as an Independent Conservative, standing against the India Bill. In November of the same year at the General Election he stood as an official Conservative for the West Toxteth Division of Liverpool, and in 1936 for the Ross and Cromarty Division of Inverness-shire, Ross-shire and Cromarty in Scotland. He was finally elected as MP for Preston in Lancashire in 1940, but lost his seat in the General Election of 1945, and though he contested the Devonport Division of Plymouth in 1950 and 1951, did not succeed in returning to Parliament.

During the war, Randolph was a major on the General Staff (Intelligence) at GHQ Middle East, in 1941, serving in the Western Desert, North Africa, Italy and Yugoslavia [now Bosnia and Herzegovina, Croatia, Kosovo, North Macedonia, Montenegro, Serbia, and Slovenia], where he formed part of the Fitzroy Maclean mission to General Tito in 1944. In later life, he was an honorary Fellow of Churchill College, Cambridge (1965) and also a Trustee for the Winston Churchill Memorial Trust in 1967.

Following the end of his political career, Randolph turned to authorship and journalism. His publications include: "They Serve the Queen", 1953; "The Story of the Coronation", 1953; "Fifteen Famous English Homes", 1954; "What I Said about the Press", 1957; "The Rise and Fall of Sir Anthony Eden", 1959; "Lord Derby, 'King of Lancashire'", 1960; "The Fight for Tory Leadership", 1964; and his memoirs, "Twenty-One Years", 1965. He then began the early volumes in his father's biography working on his father's papers which were stored in a purpose built metal outhouse, "Winston S. Churchill: Volume I, Youth, 1874-1900", 1966; Volume II, "The Young Politician, 1901-1914", 1967 and edited "Winston S. Churchill: Companion Volume I, Parts I and II", 1967. With his son, Winston S. Churchill junior, he also wrote "The Six Day War", 1967. Randolph also edited collections of his father’s speeches: "Arms and the Covenant", 1938; "Into Battle", 1940; "The Sinews of Peace", 1948; "Europe Unite", 1950; "In the Balance", 1951; "Stemming the Tide", 1953; "The Unwritten Alliance", 1961. Randolph was a keen and knowledgeable gardener and was proud of the gardens at his house at Stour, East Bergholt, Suffolk.

Randolph Churchill died on 6 June 1968.