During his career, Stewart was regarded as one of the hardest bodycheckers in the National Hockey League. He also carried the heaviest stick in the league, explaining that "I don't use it for scoring. I use it for breaking arms". Stewart was known for his large grin when hitting opponents; teammate Ted Lindsay noted "when he had that smile, it was time for the opposition to look out". He led the league with 73 penalty minutes in 1945–46, and in the late 1940s, his rivalry with Milt Schmidt of the Boston Bruins was so intense that their physical interactions occasionally overshadowed the games themselves.