Born in New York City. He left school to join the Marines and fought during WW II, being badly wounded in June 1944 and invalided home. He then established an amateur off-Broadway acting career before moving to Hollywood in 1950.
He quickly became a popular figure in supporting roles, initially always playing some kind of 'heavy'. His debut was in You're in the Navy Now (1951), but he also appeared in Don Siegel's Duel at Silver Creek (1952), being unpleasant to Gloria Graham in The Big Heat (1953), as well as archetypal baddie in Hangman's Knot (1952), Eight Iron Men (1952), Seminole (1953), Gun Fury (1953), and Bad Day at Black Rock (1954) among others.
His roles improved (e.g. Attack! (1956), The Missouri Traveller (1958)) but it took over a hundred episodes as Lieutenant Frank Ballinger in the successful television series M Squad to give him enough clout to star. He had solid roles in The Comancheros (1961), The Man Who Shot Liberty Valance (1962) and Donovan's Reef (1963). Aided by a great director (Don Siegel) he starred in the ground-breaking The Killers (1964) playing a organised, efficient, business-like assassin.
Lee Marvin won the 1965 Academy Award for Best Actor for his performance in Cat Ballou. Following roles in The Professionals (1966) and The Dirty Dozen (1967) he starred in the influential John Boorman film Point Blank (1967). Another Boorman film, the commercial flop Hell in the Pacific came the following year, co-starring Toshiro Mifune. He had a hit song with "I Was Born Under a Wandering Star" from the western Paint Your Wagon (1969).
He generally starred in 'easier' films in the 1970s and 1980s, down-playing the clarity and cruelty of his earlier roles. His 1970s films were Monte Walsh (1970), Prime Cut (1972), Pocket Money (1972), The Emperor of the North Pole (1973), The Spikes Gang (1974), The Klansman (1974), Shout at the Devil (1976), The Great Scout (1976), Cathouse Thursday (1976), Avalanche Express (1978). One last solid performance was extracted from him by Samuel Fuller for The Big Red One (1980). His remaining films were Death Hunt (1981), Gorky Park (1983), Dog Day (1984), The Dirty Dozen: The Next Mission (1985), with his final appearance being in The Delta Force (1986).
His brother was a two star general in Army Intelligence.