Mal St. Clair, the son of a renowned architect, was born and educated in California. Prior to his entry into the film industry, he worked as a cartoonist for the Los Angeles Express.
St. Clair's first job in the film industry was as an extra and gagman at Keystone in 1915. Following his service in World War I, he returned to the film business, initially working as a director for both Fox and Mack Sennett.
Mal St. Clair demonstrated a talent for slapstick farce, elegant domestic comedy, and action films. He was also able to effectively manage the temperamental movie queens of Hollywood, including Pola Negri, Clara Bow, and Joan Crawford.
St. Clair's most fruitful collaborations were with Harold Lloyd and Buster Keaton in the 1920s. One of his most notable films with Keaton was The Goat, a breakneck farce based on mistaken identity.
He also produced the hit social comedies Are Parents People? and The Grand Duchess and the Waiter. Of the latter, Mordaunt Hall of the New York Times commented that "dull moments" were "conspicuous by their absence".
Mal St. Clair directed an early version of Gentlemen Prefer Blondes, but unfortunately, no copies of this film are known to have survived. One of his notable non-comedic efforts was the Philo Vance mystery The Canary Murder Case, which starred William Powell, Jean Arthur, and Lupe Velez, and received critical acclaim.
The New York Times praised St. Clair's direction, stating that "his flashes of the canary swinging on a trapeze in a theatre are so excellent that they bring to mind the photographic feats in Variety".
St. Clair's career began to decline with the advent of sound, but he was somewhat reinvigorated with the all-star Hollywood Cavalcade in 1939, for which he directed the Keystone Kops chase sequences.
Between 1943 and 1945, he directed four Stan Laurel and Oliver Hardy features when the team left Roach and MGM for 20th Century-Fox. However, the studio's attempt to revive the great slapstick comedies of the 1920s was unsuccessful.
After his output declined somewhat, St. Clair continued to work on a few minor films for Sol M. Wurtzel's B-unit. He stood at an impressive 6'3" (or 6'7" according to some accounts),earning the distinction of being known as "the tallest director in Hollywood".