Primarily a third baseman, he appeared in one Major League Baseball game for the St. Louis Cardinals in 1911.

He started his professional baseball career in 1909, playing for the Ohio State League's Portsmouth Cobblers.

Conwell made his major league debut on September 22, 1911; he struck out in his only at bat and committed an error on his only chance in the field.

[2] The 1915 season was the last that Conwell played for Portsmouth, and he was, in the opinion of one sportswriter, the best third baseman in the Ohio State League.

After playing only 12 games in 1918, he finished his professional baseball career with one season for the Evansville Evas of the Illinois–Indiana–Iowa League.