Numminen started his career with his local team, Tappara, in the SM-liiga. Drafted in the second round (twenty-ninth overall) in the 1986 NHL Entry Draft by the Winnipeg Jets, Numminen moved to North America in 1988 to play for the Jets. He moved with the team as it became the Phoenix Coyotes before the 1996–97 season. He played in the NHL All-Star Game in 1999, 2000 and 2001. After fifteen seasons playing for the Winnipeg/Phoenix organization, Numminen was traded to the Dallas Stars in July 2003, for Mike Sillinger. Numminen took a break from hockey during the 2004–05 NHL lockout, then signed as a free agent with the Buffalo Sabres.