As an 18-year old Napier was rated as the top player in Canada born in 1957 by pro scouts. He had an impressive 223 points in 131 games during two seasons for his hometown team Toronto Marlboros in the OHA. In his last season with the Marlies, 1974-75, Napier led the team to the Memorial Cup as well as being named to the 1st All-Star team. He also led all scorers in goals (24) and points (48) in the playoffs.
Despite still having two years of junior eligibility remaining, he signed as an under-age junior with the WHA Toronto Toro's May 1975. Napier was an instant hit in the WHA, recording 93 points, and was the only rookie to finish among the league's top 50 scorers. He also was voted as the WHA rookie of the year. In his sophomore season Mark exploded for 60 goals, one of only 8 players to do so in WHA history.
Napier was a spectacular skater, blessed with tremendous speed and acceleration. He also had good balance, skating with his legs wide apart forming a low center of gravity. He maintained his fine speed until he was well past 30. Mark thrived on fast-breaks, transition offense and two-on-one situations.
He was drafted from the Birmingham Bulls (WHA) by Montreal Canadiens in the 1st round,10th overall of the 1977 entry draft. The Montreal fans loved his eye-pleasing end-to-end rushes and his streaky goal scoring exploits.
Often paired with fiery Doug Risebrough, Napier led Montreal in goals three consecutive season with 35 tallies in 1980-81 and 40 in back to back seasons in 1982 and 1983. On January 23rd, 1982 he set the team record for fastest two goals from the start of a game, scoring twice in the opening 38 seconds against Calgary.
Early into the 1983-84 season Napier Mark was traded to Minnesota together with fellow speedster Keith Acton a draft pick for strapping center Bobby Smith. After a short stint in Minnesota, Mark was traded to Edmonton for Gord Sherven and Terry Martin on January 24, 1985. The deal to Edmonton was a jackpot since it gave him two Stanley Cup rings. He also got to play with brother in law Pat Hughes.
His last stop in the NHL came when he was traded from Edmonton to Buffalo on March 6, 1987 with Lee Fogolin in exchange for Normand Lacombe, Wayne van Dorp and future considerations. Mark closed out his solid NHL career in 1988-89, totaling 767 games and 541 points (235 goals and 306 assists). In the WHA he had 254 points in 237 games.
Interestingly, Napier finished his career wearing jersey #65 back when such NASCAR numbers were not so common place. Since his favored #9 was already in use courtesy of Danny Gare, Napier chose 65 because of his involvement with the charitable Cystic Fibrosis Foundation where he was an honorary chairman. The terrible disease is often mispronounced by its youngest victims as Sixty Five Roses, leading to the annual fundraising and awareness campaign by the same tagline. Napier brought further attention to the cause by donning the jersey number.
Napier went on to play in Italy between 1989-93 where he continued to rely on his fine speed. He played for Bolzano, Varese and Milano becoming the Italian champ three out of the four years. Mark led the league in goals and points in both 1990 and 91, as well as assists in 1991. In 128 games Mark scored a whopping 376 points.