Max McNab was born in the small town of Watson, Saskatchewan in 1924 and played his minor hockey in Saskatoon. He missed two years of hockey in 1944 and 1945 during World War Two. Upon returning to competition he joined the Regina Caps in 1945-46.
The Detroit Red Wings owned the NHL rights to McNab and he played with the Omaha Knights in 1946-47. Thanks to a strong offensive showing, where he tallied 20 goals in 37 games, he was granted a 12-game promotion to the Red Wings in 1947-48. McNab earned a regular spot on the roster the following year, suiting up for 51 games, responding with 23 points. In 1949-50 he played in 65 games with Detroit, but his offensive production tailed off considerably, and he was demoted to the minors the following year. Although he had a good comeback season with the AHL's Indianapolis Capitals in 1950-51, he was forced to sit out the entire 1951-52 season recovering from back surgery.
McNab was able to rebound from his back injuries, but was never again able to raise his game to the NHL level. He played the last seven years of his career with the New Westminster Royals of the WHL and helped coach the club for part of 1952-53. At 30, McNab proved he still was a quality hockey player, winning the league MVP award, on the strength of an 81-point season in 70 games. He also prided himself on playing clean hockey and served just four minutes in penalties.
McNab began a post-playing career in hockey management in 1961-62 when he took on the role of general manager and coach of the San Fancisco Seals of the WHL. His next job was coach of the WHL's Vancouver Canucks before accepting the dual role of coach and GM of the San Diego Gulls prior to the 1966-67 season. By 1971 he was the team's Vice President. In the summer of 1974, McNab was recognized as having one of the best business minds in the game and was subsequently named the President of the Central Hockey League. The irony was not lost on the fact McNab was selected to tidy up the league's somewhat tarnished image, as it had been long known as one of the toughest and dirtiest leagues in North America. McNab, renowned for his extraordinarily clean style of hockey during his playing days, was looked upon to bring a new image to the tarnished league. However, he remained in the job for just one year when an offer to become general manager of he NHL's Washington Capitals arose. He remained with the Caps until 1982 and also served as Team Canada's GM for the 1982 World Championships.
In the autumn of 1982, McNab joined the New Jersey Devils as the team's Vice President of Hockey Operations. He also was the team's GM until September, 1987 when he was promoted to Executive Vice President, a position he kept until his retirement in the early 1990s.
McNab's son Peter also enjoyed a career in hockey, playing in the NHL with four teams, including the Boston Bruins where he enjoyed the bulk of his success.