Thompson made his Major League debut in 1949 for the Braves. After the season, he was traded to the Dodgers and spent 1950 with their top minor league club, the International League's Montreal Royals. He led the Royals in all three triple crown categories and was promoted to the Major League team in 1951. As a backup outfielder in 1951, Thompson hit just .229. He had the lowest batting average and OPS of any Dodger player with over 100 at-bats, and Brooklyn lost the pennant by one game.