Proulx attended Université Laval, majoring in law, and played for the Rouge-et-Or from 2001 to 2004. Over 18 games between 2002 and 2004, he intercepted five passes for 74 yards and a touchdown, scored two touchdowns on punt returns, and recorded 54 tackles, six sacks, seven pass knockdowns, and two forced fumbles. He won back-to-back Vanier Cups with Laval in 2003 and 2004 and was awarded the Bruce Coulter Award as the most outstanding defensive player in the 2004 Vanier Cup.
2008 CFL season may be considered his breakthrough season, however. He had been scheduled to start at safety but suffered a hamstring injury at the beginning of the season. Nevertheless, he recovered to dress for 11 games, including five starts, and has moved ahead of Étienne Boulay on the depth chart.
He studied for the bar in Montreal in 2007 and pursues a career in law during the off-season and intends continue upon his retirement.
On March 1, 2011, Radio-Canada announced on its website that Proulx will officially announce his retirement from professional football the next day at the age 29.