At the 2016 World Junior Championships Hischier was the youngest player for Switzerland, and the second-youngest player overall. He also participated in the 2017 World Juniors, scoring four goals and had seven total points in five games, the most by any player eligible for the 2017 NHL Entry Draft. Hischier also partook at the 2017 IIHF World U18 Championships, and finished with six points in five games as Switzerland lost in the quarter-finals.