From 1916 to 1929, he played as an outfielder in Major League Baseball for the Detroit Tigers, Cincinnati Reds, Philadelphia Phillies, New York Giants, St. Louis Cardinals, and Boston Braves.

[4] Writing for the North American Newspaper Alliance, Walter S. Trumbull said that Harper had likely won the pennant for St. Louis with that performance.

Before the 1936 season, he was traded from El Dorado to the Jackson Senators of the Cotton States League in exchange for a player named Doodle Rushing.

[7] In 1936, Harper's last year playing professional baseball, he hit .297 in 118 games between the Jackson Senators and the Augusta Tigers of the South Atlantic League.

[1] By February 1937, Harper was living in Shreveport, Louisiana; he was not under contract with any team, but he indicated that he would entertain playing, managerial or executive offers in baseball.