His NHL career would begin in 1971 when he was signed as a free agent by the St. Louis Blues. After three seasons with the Blues, he was traded to the Philadelphia Flyers in September 1974. While in Philadelphia, Wayne toiled as a backup to Bernie Parent for the 1974-1975 season. When Parent suffered a pinched nerve in his neck during the 1975-1976 pre season that required surgery, Stephenson became the Flyers starting goaltender and retained the job when Parent returned late in the season but couldn't regain his previous All Star form. During that year, Stephenson allowed one goal in the Flyers' win over the Soviet Red Army hockey team, a victory Stephenson referred to as the highlight of his career. Stephenson sought a salary increase to reflect his new responsibilities and value to the team in 1976 but management held firm and he returned to the Philadelphia lineup after a two-month holdout. The friction generated by the dispute fueled his exit from Philadelphia. Stephenson was traded to the Washington Capitals prior to the 1979–80 NHL season and played there for two seasons before retiring.

Awards and achievements:

• MJHL First All-Star Team (1965)
• MJHL Top Goaltender (1965)
• MJHL Most Valuable Player (1965)
• Turnbull Cup MJHL Championship (1965)
• Played in the World Championships for Team Canada (1967 and 1969)
• Olympic bronze medalist (1968)
• Stanley Cup championship (1975)
• Played in NHL All-Star Game (1976 and 1978)
• "Honoured Member" of the Manitoba Hockey Hall of Fame