St. Laurent played for both the Toledo Goaldiggers of the IHL and the Maine Mariners of the AHL, where he was part of the Calder Cup-winning team during the 1983–84 season.

The Flyers traded St. Laurent to the New Jersey Devils on 27 September 1984 for future considerations (though he remained with the Mariners while assigned to the AHL.)

After a brief reassignment to the minors, St. Laurent was recalled and given his first NHL start on 27 March 1986, making 24 saves to earn a 1–0 shutout victory.

)[3] With the emergence of Tim Cheveldae from the Red Wings' depth chart, St. Laurent was traded to the New York Rangers for cash on 26 June 1990.

St. Laurent became the veteran third-string goaltender behind Sean Burke (who was in the midst of a contract dispute) and Trevor Kidd, a then-drafted prospect for the Calgary Flames.