His first acting role came in the 1980 Disney film Midnight Madness as Scott Larson. He also provided the voice for Chance, the American Bulldog in the 1993 Disney film Homeward Bound: The Incredible Journey, and in its sequel, Homeward Bound II: Lost in San Francisco.
He also voiced Michael in the episode "The Curse of Candace" of the Disney Channel animated series, Phineas and Ferb. He also played Michael Chapman in the 1993 Touchstone Pictures film Life with Mikey.
Since 1991, Fox was diagnosed with Parkinson's disease, and has since become an advocate for the disease's cure. Prior to his semi-retirement from acting in 2000, he was a principal character on Spin City.
Despite this, he recently starred in The Michael J. Fox Show on NBC.