Hamelin, who lives in Montreal, started shorttrack when he was five. He competed internationally for the first time in January 2005 at the Junior World Championship. There he missed the finals in all individual races, but achieved this with the 2000 m relay and won bronze. Hamelin also won the bronze medal a year later when he reached third place over 1000 meters at the Junior World Championships. Since he had also placed himself at the front in the other races, he was also allowed to take part in the superfinal of the top eight and just missed the podium in fourth. With the Canadian season he even came second and won silver.
In the 2006/07 season, Hamelin did not start at any major event, but only at national races. Only one winter later he was nominated for the first time for the Short Track World Cup 2007/08 by the Canadian team. He was able to achieve results in all disciplines, but especially over 500 meters he placed in the top twenty places in the overall World Cup because he even finished the last race of the season over this distance in third place on the podium. At the 2007 World Cup, Hamelin was eleventh. In the 2007 season, Hamelin also set a new world record over 500 meters, which, however, only lasted for a short time and was undercut during the season.
Hamelin also got off to a good start in the 2008/09 Short Track World Cup and achieved a podium finish for the second time at the second World Cup in Vancouver , this time finishing third over the 1000 meters. The winner of that race was his older brother Charles Hamelin .