Stapleton was briefly the property of the Toronto Maple Leafs in June 1965 as part of a trade with the Bruins, but he was left unprotected in the intra-league draft and was claimed the next day by the Chicago Black Hawks. Wearing number 7, he played some games with the Hawks' Central Hockey league affiliate, the St. Louis Braves, in 1965–66, but they would be the final minor league games of his career. Stapleton remained in the NHL for eight seasons with the Black Hawks, and was named Second Team All-Star three times (1966, 1971, and 1972). Stapleton played with the Black Hawks in the Stanley Cup finals in 1971 and 1973. His highest scoring season was 1969, where his 50 assists set a new NHL record for assists in a season by a defenceman (broken the next year by Bobby Orr).