Johnson made his major league debut on April 20, 1947, starting game 2 of a doubleheader against the Philadelphia Athletics at Shibe Park. He was the winning pitcher in the 10-inning, 3–2 Yankee victory, and went on to have a 4–3 record for the 1947 World Series Champions.
Johnson pitched both as a starter and in relief during his long, well-traveled career. His best season statistically was in 1954 with the White Sox. He won 8, lost 7, had a 3.12 earned run average, and finished in the American League Top ten in games pitched, saves, and shutouts.