Hamelin, of Sainte-Julie, Que., had a time of two minutes 27.209 seconds. He was edged out on the last lap by South Korea`s Yun-Jae Kim, who took silver behind teammate Do Woon Sin.
"The day was good (but) the ice was not as good as I had expected," said Hamelin.
"I thought I had the legs to win one. I had my place stolen by the Korean behind me with a little bump, so he took my spot and I finished third. I'm happy with my day and it leaves me in a good position for tomorrow and Sunday."
Sin won in 2:27.062 and Kim finished in 2:27.101.
It's Hamelin's second career bronze in the 1,500 at the world championships and he also has a silver in the event. In 10 years of competition at the worlds, he has won a total of four gold, six silver and five bronze medals at various distances.
St. Gelais, from St. Felicien, Que., took advantage of a two-skater spill that included teammate Valerie Maltais to move into third in 2:24.694.
"It's short track, we always expect something like that during a race," said St. Gelais. "It was my first A final in the 1,500 and I'm proud of what I did. I hope I'm going to have a medal in a better way."
Seung-Hi Park took gold in 2:23.634 and fellow South Korean Suk Hee Shim earned silver in 2:23.755. Maltais had to settle for fifth.
Michael Gilday of Yellowknife joined Hamelin in the final and finished in fifth with a time of 2:27.437. It was his first world championship race.
Olivier Jean of Lachenaie, Que., who did not race in the 1,500 during the World Cup season, was 17th.
Marie-Eve Drolet of Laterriere, Que., was eliminated after finishing third in her quarter-final heat.
The Canadian women`s relay team finished second in the semifinals to advance to Sunday`s final. Jessica Hewitt of Kamloops, B.C., teamed up with Drolet, Maltais and St. Gelais for a time of 4:19.466. South Korea was first in 4:15.233.