He played six years as a second baseman in Major League Baseball: 1922–23 with the New York Giants, 1928 with the Chicago Cubs, and 1929–31 with the Boston Braves.

A Roxbury, Massachusetts, native, Maguire attended Boston Latin School and the College of the Holy Cross.

He made his professional debut in the Major Leagues for the Giants at the end of the 1922 season, playing in five games for them that year.

Things started off with a bang, as Maguire hit his first Major League home run on Opening Day off Cincinnati Reds pitcher Dolf Luque.

Replacing Hornsby was a difficult task, and Maguire slumped in 1929 for the cellar-dwelling Braves, as his numbers slipped both offensively and defensively.