Giles had a very productive career in the Negro Leagues. He played for the Kansas City Royal Giants (1925), Gilkerson Union Giants (1926 and 1929), Kansas City Monarchs (1927-28, 1932-34, and 1939), St. Louis Stars (1930-31), Philadelphia Stars (1932, 1938), Detroit Wolves (1932), Homestead Grays (1932), Baltimore Black Sox (1933), Brooklyn Eagles (1935), New York Black Yankees (1936-38), Pittsburgh Crawfords (1938), and Satchel Paige's All-Stars (1939).
Giles was a superb Negro League first baseman and a lifetime .300 hitter. All-star Ted "Double Duty" Radcliffe called Giles "the best colored first baseman I ever saw..." Giles played for the St. Louis Stars, one of the Negro Leagues' greatest teams, from 1929 through 1931.
In a 1930 eight-game series against major league all-stars, the Stars won six games against the pitching of Willis Hudlin, George Uhle, and Earl Whitehill. The Stars won the Negro National League pennant in 1930 and 1931. In the twilight of his career, Giles played for the Satchel Paige All-Stars. His final contribution to pro baseball was as manager of the 1935 Brooklyn Eagles.