Cooley was born on March 29, 1873, in Leavenworth, Kansas. He began his Major League career in 1893, playing for Topeka, Kansas, before playing for the St. Louis Browns of the National League (NL). Although the seventh youngest player in the league during his first season, he batted .346, which remained a career-high. Defensively, Cooley was a utility player, starting at multiple positions for the Cardinals. On September 30 of 1893, Cooley recorded six hits against the Boston Beaneaters. He played for St. Louis in 1894, nearly doubling his at bats (206) and games played (54).