He was a pitcher in Major League Baseball (MLB) for nine seasons with the Boston Red Sox, Washington Senators, and Cleveland Indians between 1940 and 1952.

Though plagued by chronic arm problems, Harris helped the Red Sox win the 1946 American League pennant en route to the 1946 World Series against the St. Louis Cardinals.

Harris began his professional career in Minor League Baseball during the 1938–1940 seasons playing for farm teams of the Boston Red Sox.

He joined the starting rotation in 1941, along with Dick Newsome, Charlie Wagner, Lefty Grove and Joe Dobson.

After being out of professional baseball for four seasons, Harris compiled a 17–9 record in 1946, as the Red Sox ran away with the pennant.