A full international since 2010, Vargas has earned 100 caps for Chile, scoring 40 goals. He was part of their squad at the 2014 FIFA World Cup, the 2017 FIFA Confederations Cup, and the Copa América in 2015, 2016, 2019 and 2021. He would finish as top scorer in Chile's title-winning 2015 and 2016 Copa América campaigns.