Locatelli made his debut with the Italy U21 team on 23 March 2017, in a friendly 2–1 win against Poland. In June 2017, he was included in the Italy under-21 squad for the 2017 UEFA European Under-21 Championship by manager Luigi Di Biagio. Italy were eliminated by Spain in the semi-finals on 27 June, following a 3–1 defeat.