The 2004–2005 season was a breakout year for Hamelin. This was the first year that he skated every event in the World Cup. He finished third overall in the 500 m, 4th in the 1000 m, 5th in the 1500 m, and 5th overall on the season. He continued to skate on the relay team which finished 1st in the final standings. The real success of his season would come at the 2005 World Championships. He managed a silver in the 500 m and two 4th-place finishes in the 1000 m and 3000 m. This allowed him to finish fourth overall in the standings. That year he was also a part of the gold medal-winning Canadian squad at the World Team Championships.