On December 6, 1973, Mason's contract was purchased by the New York Yankees from the Rangers. He was a member of the Yankees during the 1976 World Series against the Cincinnati Reds. Although he did not play in the 1976 American League Championship Series, he played three games in the World Series. In his only plate appearance of the series, Mason hit a home run off Pat Zachry. This turned out to be Mason's only postseason appearance, and the Yankees' only home run of their four-game series loss. It was also the 500th home run in the history of the World Series.