In 2010, Vatanen represented Finland internationally at the junior level (2010 World Junior Championships held in Saskatchewan) and at the senior level (2010 World Championships held in Germany). At the end of the 2009–10 season, Vatanen also became the highest-drafted Finnish player in Kontinental Hockey League (KHL) history when he was selected second overall in the 2010 KHL Junior Draft by Metallurg Novokuznetsk.