At the 2012 Summer Olympics, Peillat competed for the National team. Gonzalo won the bronze medal at the 2014 World Cup where he was the top scorer of the tournament with 10 goals and the gold medal at the 2015 Pan American Games in Toronto, Ontario, Canada. His best achievement came at the 2016 Summer Olympics where he won the gold medal for Argentina. He scored 11 goals in the tournament and became the highest scorer. After a dispute with the Argentine head coach German Orozco in January 2019, Peillat took a break from the Argentine national team.