Gagnon's first World Cup podium came in March 2012, a third-place in a slalom at Åre, Sweden. Her first victory was in January 2014, a combined event at Altenmarkt, Austria. which was the first podium for a Canadian in a World Cup combined event in thirty years. The previous day she scored her first World Cup points in downhill at the same venue. That season she also took her first top ten World Cup finishes in super-G, finishing tenth and sixth in races in Lake Louise and St. Moritz respectively. At the Winter Olympics, Gagnon crashed out of the slalom run of the combined, dislocating her shoulder, before failing to finish the super-G and giant slalom, and securing a ninth place in the slalom. She finished thirteenth in the overall World Cup standings and sixth in slalom.