Born in Montreal, Quebec, she was one of the Canadian pioneers in early Hollywood. Starting as a film extra in 1920, she was already a popular star when she married MGM's second-in-command Irving Thalberg in 1927 (they had two children). Shearer won an Academy Award for Best Actress for her role in The Divorcee (1930). She was nominated the same year for her role in Their Own Desire, in 1931 for her role in A Free Soul, in 1934 for The Barretts of Wimpole Street, in 1936 for Romeo and Juliet, and in 1938 for Marie Antoinette (said to be Shearer's favorite role).
Thalberg died in 1936, after which his widow embarked upon a series of little known but enthusiastic love affairs, including one with teenage film star Mickey Rooney and tough-guy actor George Raft. Shearer retired from acting in 1942, marrying that same year Martín Arrouge, a ski enthusiast quite a few years her junior. Confounding the skeptics, they were still happily married at the time of Shearer's death, though in her declining years she reportedly called Arrouge "Irving."
She has a Star on the Hollywood Walk of Fame at 6636 Hollywood Blvd. and is buried at Forest Lawn Memorial Park Cemetery, in a crypt emblazoned with the name "Norma Arrouge," next to film star Jean Harlow.