St-Jean made his debut in the Speed Skating World Cup at the beginning of the 2013/14 season in Calgary and finished ten and eleven in the B World Cup over 500 m. He finished eighth at the 2014 Sprint World Championship in Nagano . In the A World Cup, he started for the first time at the beginning of the 2015/16 season in Calgary and achieved 14th place over 1000 m. As the season progressed, he won his first World Cup victories in the team sprint in Salt Lake City and Heerenveen . In addition, he finished second in the team sprint in Heerenveen at the World Cup finals and second in the 500 m World Cup in Inzell . From 2016 to 2018 he won the silver medal over 1000 m at the Canadian championships. At the individual distance world championships in 2016 in Kolomna he took sixth place over 1000 m and at the individual distance world championships in 2017 in Gangwon-do 12th place over 1000 m. In November 2017, he won his third World Cup victory in the team sprint in Heerenveen.
Personal bests
500 m 34.46 sec. (installed on November 22, 2015 in Salt Lake City)
1000 m 1: 07.65 min. (installed on December 10, 2017 in Salt Lake City)
1500 m 1: 49.39 min. (installed on January 2, 2014 in Calgary)
3000 m 4: 02.12 min. (installed on August 15, 2015 in Calgary)
5000 m 9: 19.28 min. (established December 15, 2007 in Quebec)
Canada
Salt Lake City 1
Heerenveen 2