Pearson was bought by Manchester United after they were relegated to the Second Division and was instrumental in getting the club promoted back to the First Division the next season by scoring 17 goals. Every time he scored a goal he would celebrate with a raised right fist. He was in the team that lost 1–0 to Southampton in the 1976 FA Cup Final. The next year Pearson helped Manchester United win the 1977 FA Cup Final against Liverpool, scoring the first of Manchester United's goals in their 2–1 win. He was sidelined for all of the 1978–79 season due to a knee injury but made a full recovery before leaving Manchester United for West Ham United in August 1979.