Thompson began his National Hockey League (NHL) career with the Boston Bruins in the 1928–29 season after his contract was purchased by Boston manager Art Ross. Despite having never seen Thompson play, Ross had heard about Thompson's good reputation in Minnesota. In his first game, he posted a shutout, becoming the only Hockey Hall of Fame goaltender to accomplish this feat. In his first season, he appeared in all 44 of the Bruins' games, posting 12 shutouts and a 1.15 goals-against average, the second lowest goals-against average in NHL history to date, second to George Hainsworth's 0.98 GAA. Hainsworth set his record that same season. Placing first in the American Division, the Bruins had a perfect record in the playoffs en route to their first Stanley Cup victory, defeating the Montreal Canadiens and the New York Rangers. Thompson recorded three shutouts in the five playoff games, and allowed only three goals.