Cabot was born Étienne de Pelissier Bujac, Jr., in Carlsbad, New Mexico, to a prominent local lawyer, Major Etienne de Pelissier Bujac, Sr. (Dec. 22, 1867 - April 12, 1932), and Julia Armandine Graves (1864-1904) of New York City, who died shortly after giving birth to her son.
Etienne, Sr., was the son of John James Bujac, a lawyer and mining expert in Baltimore, Maryland. Etienne, Sr., graduated from Cumberland School of Law near Nashville, Tennessee, and served in the United States army during the Spanish-American War and the Philippine Insurrection before settling in Carlsbad.
Cabot graduated from Sewanee Military Academy in 1921 and briefly attended the University of the South in Sewanee, Tennessee, but left without graduating. He worked at many jobs, including as a sailor, an insurance salesman, oil worker, surveyor, and prize fighter; he also sold cars, handled real estate, and worked at a slaughterhouse. A meeting with David O. Selznick at a Hollywood party started his acting career.
Cabot appeared in nearly one hundred feature films. He made his debut in 1931 in Heroes of the Flames. He played a soldier who seduced a naive woman (portrayed by Irene Dunne) and got her pregnant as he left for the war, in Ann Vickers (1933). He then starred in the blockbuster film King Kong, which became an enormous success and established Cabot as a star.
He also played villains, appearing as a gangster boss in Let 'Em Have It (1935) and as the Huron warrior Magua opposite Randolph Scott in The Last of the Mohicans (1936). He starred with Spencer Tracy, playing the leader of a lynch mob in Fritz Lang's first Hollywood film, Fury (1936), and with Errol Flynn in Michael Curtiz's epic western Dodge City, which became one of Warner Bros.'s biggest hits.
He tested for the lead role of The Ringo Kid in John Ford's Stagecoach (1939), but John Wayne got the part. A consistent box office draw, Cabot appeared in many movies at many studios before leaving Hollywood to serve in World War II.
Cabot enlisted in December 1942 and, after Officer Training School in Miami Beach, became a first lieutenant in the U.S. Army Air Forces.
Cabot headed back to Hollywood and fell in with John Wayne (whose career was then in the ascendant, and who would become a major force in American film-making over the next two decades) on the set of Angel and the Badman (1947) and became part of Wayne's circle, this relationship paying off in the 1960s when Wayne cast him in ten of his films: The Comancheros (1961), Hatari! (1962), McLintock! (1963), In Harm's Way (1965), The War Wagon (1967), The Green Berets (1968), Hellfighters (1968), The Undefeated (1969), Chisum (1970), and Big Jake (1971).
Cabot's final screen appearance was in the 1971 James Bond film Diamonds Are Forever.
He was inducted into the New Mexico Entertainment Hall of Fame in 2012.
Bruce Cabot starred in a number of the Tales of Tomorrow episodes (1952-53), television's first sci-fi drama and an early hit for ABC.
He also appeared on other television series such as:Burke's Law - "Who Killed Holly Howard?" - Thomas Matherson (1963)
Bonanza! - "A Dime's Worth of Glory" - Sheriff Reed Carrimore (1964)
Daniel Boone - "The Devil's Four" - Simon Bullard (1965)
Cabot was married three times, in Florida to Mary Mather Smith with whom he divorced prior to moving to Hollywood, and to actresses Adrienne Ames and Francesca De Scaffa.
He was one of Errol Flynn's social pack for several years but they fell out during the production of the unfinished The Story of William Tell. Flynn was producing the film and asked Cabot, whom he described as "an old, old pal," to perform in it, knowing that Cabot was finding it hard to get work in Hollywood at that time. However, when Flynn's production partners defaulted, the production halted, leaving Flynn stranded in Rome facing financial ruin. Cabot, in an attempt to get paid when other cast members were working without pay, had Flynn's and his wife Patrice Wymore's personal cars and clothing in their Rome hotel seized. Flynn wrote angrily in his autobiography of what he termed Cabot's "betrayal." Eleven years after Flynn's death, in an interview in England in 1970, Cabot paid tribute to him as a critically underestimated actor, but said that Flynn had destroyed himself through narcotic addiction.
Cabot died in 1972 at the Motion Picture Country Home at Woodland Hills, California from lung cancer and was buried in his hometown of Carlsbad, New Mexico.