Thompson was born in Winchester, Massachusetts. He started his pro career with a tryout with the Boston Olympics in the 1938–39 season. He returned for two seasons with the Olympics, scoring 16 goals in 35 games in his rookie season. In 1941–42, he made his NHL debut with the Bruins, playing three games, while mainly playing for the Hershey Bears and St. Paul Saints of the American Hockey Association (AHA). From 1942–1945, Thompson fought in World War II. He returned to the Olympics and played every season for the club until 1950, with a ten-game call-up to the Bruins in 1948–49 and nine games for the Bears that same season.