Spinks was a member of the 1976 United States Olympics team and won a gold medal in the boxing competition. He became a professional boxer in 1977 and won the light heavyweight championship in 1981. In 1985 he fought heavyweight champion Larry Holmes and beat him for the title. It was the first time a light heavyweight champion had become heavyweight champion. He beat Holmes again in a rematch and defended his title another two times before losing to Mike Tyson in 1988. He never fought again.
Michael Spinks is the brother of heavyweight champion Leon Spinks.