He played junior for the Sherbrooke Castors and was an offensive defenceman there, putting up impressive point totals.
Selected 34th overall by the Atlanta Flames in the 1972 NHL Draft, Lemieux played parts of two and a half seasons with the Flames before he was traded to the Washington Capitals in the deal that sent Bill Clement to Atlanta in 1976.
Lemieux played for the Capitals through the 1977–78 season, splitting time between the Caps and the minor pros.
He retired in 1979 after spending a year with the Nova Scotia Voyageurs.
In the NHL, Lemieux played in a total of 204 games, scoring 23 goals and 63 assists.