In May 2019, Martínez was included in Lionel Scaloni's final 23-man Argentina squad for the 2019 Copa América. In Argentina's final group match against Qatar on 23 June, he scored the opening goal in a 2–0 win, which enabled them to advanced to the knock-out stages of the competition. On 28 June, in the quarter-finals of the tournament, Martínez scored the opening goal in an eventual 2–0 win over Venezuela with a back-heel in the opening ten minutes of the match; he was later named "Man of the match", and the victory enabled Argentina to advance to the semi-finals of the competition.