McLaglen claimed to have been born in Tunbridge Wells, Kent, although his birth certificate records 505 Commercial Road, Stepney in the East End of London as his true birthplace.

[11] Four years later, he moved to Winnipeg, Manitoba, Canada, where he became a local celebrity,[12] earning a living as a wrestler and heavyweight boxer, with several notable wins in the ring.

[14][15] One of his most famous fights was against heavyweight champion Jack Johnson in a six-round exhibition bout at the Vancouver Athletic Club on 10 March 1909.

[18] He landed at Basra on 10 August 1916 and served as an Assistant Provost Marshal in Mesopotamia, ending the war as a Temporary Captain.

Donald Crisp cast him in The Glorious Adventure (1922)[24][25] and he was in A Romance of Old Baghdad (1922), Little Brother of God (1922), A Sailor Tramp (1922), The Crimson Circle (1922), The Romany (1922), and Heartstrings (1922).

[26] McLaglen played leads in M'Lord of the White Road (1923), In the Blood (1923), The Boatswain's Mate (1923), Women and Diamonds (1924), and The Gay Corinthian (1924).

McLaglen played one of the titular characters of The Unholy Three (1925) in Lon Chaney Sr.'s original silent version of the macabre crime drama.

McLaglen was the top-billed leading man in director Raoul Walsh's First World War classic What Price Glory?

He starred in Hangman's House (1928) for Ford, a romantic drama set in Ireland, and The River Pirate (1928), and Captain Lash (1929).

He was reunited with Edmund Lowe and Raoul Walsh in a sequel to What Price Glory?, The Cock-Eyed World (1929), which was another huge success at the box office.

[32] McLaglen starred opposite Boris Karloff's crazed religious fanatic in John Ford's The Lost Patrol (1934) at RKO, a picture about desperate soldiers gradually losing their minds fighting Arabs in the desert of what is now Iraq.

Another highlight of his career was winning an Academy Award for Best Actor for his role in Ford's The Informer (1935), shot at RKO, based on a novel of the same name by Liam O'Flaherty.

[34] At Paramount, he was teamed with Mae West in Klondike Annie (1936), then he went back to Fox for Under Two Flags (1936) with Rosalind Russell and Ronald Colman.

[37] The latter, with Cary Grant and Douglas Fairbanks Jr., was an adventure epic loosely based on Rudyard Kipling's poem that served as the template decades later for Indiana Jones and the Temple of Doom (1984).

He supported Brian Aherne in Captain Fury (1939), and starred in Full Confession (1939) for John Farrow at RKO, the latter film being somewhat a remake of The Informer.

in the radio program Captain Flagg and Sergeant Quirt, broadcast on the Blue Network (28 September 1941 – 25 January 1942, and on NBC 13 February 1942 – 3 April 1942).

McLaglen began to be exclusively a supporting actor, with parts in Love, Honor and Goodbye (1945), Whistle Stop (1946) with George Raft and Ava Gardner,[39] Calendar Girl (1947), The Michigan Kid (1947), and The Foxes of Harrow (1947).

McLaglen was later nominated for another Oscar, this time for a Best Supporting Actor for his role opposite John Wayne in The Quiet Man (1952).

[40] He continued to be in demand as a support actor in action films: Fair Wind to Java (1953) with Fred MacMurray and Prince Valiant (1954) with James Mason and Robert Wagner.

McLaglen had a rare late career lead role in City of Shadows (1955) at Republic with Patricia Crowley, and he was second-billed in Bengazi (1955), but he went back to supports with Lady Godiva of Coventry (1955).

He had a cameo in Around the World in 80 Days (1956) with David Niven and Cantinflas, then had another lead in The Abductors (1957), directed by his son, Andrew V. McLaglen.

Toward the end of his career, McLaglen made several guest appearances on television, particularly in Western series such as Have Gun, Will Travel and Rawhide.

[42] In 1933, he founded the California Light Horse Regiment, which included a "riding parade club, a polo-playing group and a precision motorcycle contingent".

[44] In 1935, McLaglen spent a reported $40,000 (equal to $888,932 today) to build his own stadium near Riverside Drive and Hyperion Avenue, near Griffith Park and the Atwater Village neighborhood of Los Angeles.

[52] On 8 February 1960, McLaglen received a star on the Hollywood Walk of Fame at 1735 Vine Street, for his contributions to the motion-picture industry.