His first podium came in 2015 at the FIS Alpine World Ski Championships 2015 when he finished 2nd in the Super G at Beaver Creek. Cook became the first Canadian man to medal in a Super G at the World Championships. He also finished twelfth in Giant Slalom at the World Championships one week later. His first FIS Alpine World Cup podium came one month later when he finished 3rd in the Super G at Kvitfjell. He won his first race eleven days later at the World Cup Finals in Meribel. Cook finished the 2015 season with five top twenty World Cup finishes, in addition to his two podiums and World Championship medal. He finished the 2015 season ranked 5th in Super G, and 30th in Giant Slalom.