Johansen was invited to take part in the Canadian national junior team's selection camp in August and December 2011. He was later named to the squad, competing in the 2011 World Junior Ice Hockey Championships, held in Buffalo, New York. Making his international debut against Russia, he scored his first goal for Canada in a 5–3 win. In the quarterfinal against Switzerland, he was named the player of the game, having scored his second goal of the tournament. He scored again in the semifinal against the United States to help Canada advance to the gold medal game, where they were defeated 5–3 by Russia. Johansen finished with three goals and nine points, third in team scoring behind Brayden Schenn and Ryan Ellis, and was named to the Tournament All-Star Team.