Merzļikins participated in the 2012 World Junior Ice Hockey Championships and 2013 World Junior Ice Hockey Championships as a member of the Latvia men's national junior ice hockey team. He was selected to the national team for the 2016 World Championship, and made his debut in the opening game against Sweden in a 2–1 overtime loss. Merzļikins also played in the 2017 World Championship and in the 2018 World Championship. In the 2018 tournament, he posted a 1.50 goals against average and .940 save percentage in six contests.