Born in St. Louis, Missouri, Ens served the Pittsburgh Pirates as a utility infielder (1922–25), player-coach (1923–25), coach (1926–29; 1935–39) and manager (1929–31).

During his 17-year active career (1908; 1910–25), Ens threw and batted right-handed, stood 5 feet, 10+1⁄2 inches (1.8 m) tall and weighed 165 pounds (75 kg).

For the next three seasons, he played a total of only 12 games, as he served as an aide to Hall of Fame manager Bill McKechnie.

During his two full seasons, 1930 and 1931, the Pirates posted 80–74 and 75–79 records, and Ens was replaced by George "Moon" Gibson for the 1932 campaign.

After his coaching days, Ens enjoyed a successful, eight-year run as manager of the Syracuse Chiefs, making the International League playoffs five times and winning three (1942–43; 1947) Governors' Cup championships.