Stapleton went on to move to Manchester United in the summer of 1981 for £900,000 (a fee set by tribunal after the two clubs could not agree) as new manager Ron Atkinson began building a team capable of challenging for silverware after a disappointing 1980-81 season under Dave Sexton. He helped United win the 1983 and 1985 FA Cups. It was in the first of those finals, when he scored against Brighton, in which Stapleton made history by becoming the first man to score for two different clubs in FA Cup Finals.United finished in the top four of the league in each of Stapleton's first five seasons at Old Trafford, and came close to winning a league title medal in the 1985-86 season after United won their first 10 league games of the season before their form slumped and they finished fourth. Atkinson was sacked and replaced by Alex Ferguson in November 1986, and Stapleton remained a regular member of the first team under the new manager, but he left at the end of the season to sign for Ajax. There, he made just six appearances and scored one goal before quickly being moved to Belgian side Anderlecht at the end of 1987, followed by a three-month loan back to England with Derby County. He then played for French club Le Havre for a season, before returning to England with Blackburn Rovers in 1989, followed by moves to Aldershot, Huddersfield Town (as player-coach) and Bradford City.