The Sarnia native played with the Sarnia Legionnaires Junior B club before spending two seasons with the Chicago-sponsored St. Catharines Teepees of the OHA. As a junior, he was often the smallest player on the ice.
After a solid year with the Sault Ste. Marie Thunderbirds of the Eastern Professional Hockey League, Stapleton was claimed by Boston in the Inter-League Draft in June 1961. The Bruins were a weak outfit at this time and were able to give Stapleton a fair 18-month trial before sending him to the minors.
Stapleton played 90 games for the Bruins and then spent nearly three years in the minors. He excelled with the Portland Buckaroos of the WHL from 1963 to 1965, where he often played center. He scored 29 goals in 1963-64 from his pivot spot.
Stapleton was voted to the NHL Second All-Star Team in 1966 and duplicated this honor in 1971 and 1972. He played with the Hawks until the end of the 1972-73 season and helped the squad reach the Stanley Cup finals in 1971 and 1973. His quick hands and lightning reflexes, combined with a hard, accurate shot, made him one of the more effective point men in the NHL. Defensively, he was a master of the poke-check and was able to consistently steer opponents away from the goal.
Stapleton and defense partner Bill White developed into one of the NHL's elite tandems. They were the key to the Hawks winning four straight West Division crowns, and in the 1972 Summit Series against the USSR they were teamed in seven of the eight games. Stapleton was on the ice when Paul Henderson scored the dramatic series-winning goal with 34 seconds left in the third period. Amid all the celebrations, he grabbed the historic puck, a treasure he preserves at home to this day. Stapleton and White were also known for their pranks that helped keep the Chicago and Canada teams loose.
Prior to the 1973-74 season, Stapleton signed with the Chicago Cougars of the WHA as player-coach. In his first year he scored 58 points in 78 games and won the Dennis A. Murphy Trophy as the league's top defenseman. He was also named to the WHA First All-Star Team. In a unique twist, he and teammates Dave Dryden, Ralph Backstrom and Rod Zaine bought the team to keep it going for the duration of the season. The club lasted one more year before folding, whereupon Stapleton joined the Indianapolis Racers.
His last pro season in 1975-76 proved very rewarding. In only its second year of operation, the Racers won the East Division championship of the WHA and came within one game of reaching the Avco Cup finals. The team started poorly but improved dramatically as Stapleton's influence on the younger players began to have an affect.
Before the start of the next season, he played in the 1974 series that pitted the USSR against the top Canadian players from the WHA. Before retiring from the game, Stapleton moved on to the Indianapolis Racers and the Cincinnati Stingers.
Whitey Stapleton left hockey in 1978 after scoring 337 points in the NHL and 238 in the WHA.