The Montreal native was never drafted by a NHL team. In three seasons with the QMJHL Chicoutimi Sagueneens Langevin scored 54 goals and collected over 450 penalty minutes. The key stat here was his penalty minutes, as that was his ticket to the NHL.
Undrafted and unsigned by a NHL team, Langevin was undeterred. In 1980-81 he signed with the Saginaw Gears of the then-lowly IHL and enjoyed a fine rookie pro season. He notched 35 goals plus 179 penalty minutes.
The Rochester Americans signed Langevin for the 1981-82 season. The Sabres and Americans had a deal where most of the players on the Amerks roster were supplied by the Sabres, but a few free agents could be brought in by the Amerks themselves. Langevin fit this bill for that season, and he filled the tough guy role admirably, but also showed decent skill. In his second season in Rochester he scored 18 goals and 43 points plus his customary 255 penalty minutes.
The Sabres were impressed enough to sign him to a contract in 1983-84, although he would mostly remain in the minor leagues with Rochester for the next two years.
By 1985-86 Langevin appeared to finally make the NHL. Langevin stuck with the team directly after training camp. the following season and got into 16 games, scoring 2 goals and 1 assist while behaving himself with only 20 penalty minutes. In a game vs. the Quebec Nordiques on November 22, 1985, Langevin blew out his knee. He would never be able to recover from the injury and was forced to retire.
It's a sad ending for a good guy who appeared to have the odds beaten.