Martínez played with the Argentina U21 squad at the 2012 Pan American Junior Championship, the 2013 Sultan of Johor Cup and the 2013 Junior World Cup before he made his debut for the main squad in 2014 at the 2014 South American Games. He won the gold medal at that tournament and made four goals. He was also part of the Argentina squad which won the bronze medal at the 2014 World Cup, which was his first World Cup. In 2018 he was selected for the 2018 World Cup, where he scored two goals in four matches. In July 2019, he was selected in the Argentina squad for the 2019 Pan American Games. They won the gold medal by defeating Canada 5–2 in the final.