He made his screen debut in National Film Board of Canada shorts, later getting into feature films via American television, often cast as a younger man undergoing initiation at the hands of older men. Sarrazin received good notices opposite George C. Scott in The Flim-Flam Man (1967) and connected with youthful audiences in the 1968 surfing saga The Sweet Ride, which co-starred Jacqueline Bisset. He also played opposite Jane Fonda in the harrowing melodrama They Shoot Horses, Don't They? (1969), which earned him a BAFTA (British Oscar) nomination for most promising newcomer, but he never seemed to get beyond the brink of stardom. In later years he took many unsympathetic character roles, including white-collar criminals, in film and television.
His Canadian films include Joshua Then and Now (1985), Malarek (1989) and La Florida, the 1993 Golden Reel Award winner produced by his brother, Pierre Sarrazin. He had a recurring role in the short-lived Canadian series The City (1999-2000), for which he received a Gemini Award nomination for best performance by a supporting actor in a series. Michael Sarrazin's other notable films include Sometimes a Great Notion (1971), Pursuit of Happiness (1971), The Groundstar Conspiracy (1972), The Life and Times of Judge Roy Bean (1972), Harry in Your Pocket (1973), For Pete's Sake (1974), The Reincarnation of Peter Proud (1975), The Loves and Times of Scaramouche (1975), The Gumball Rally (1976), Deadly Companion (1980), Captive Hearts (1988), The Peacekeeper (1996) and Fear Dot Com (2002).