Milinković-Savić represented Serbia at under-19, under-20 and under-21 levels. He played for Serbia at the 2013 UEFA Under-19 Championship, winning the gold medal. He played the full 90 minutes in four out of five games, including the final match of the competition against France that Serbia won 1–0. Subsequently, Milinković-Savić appeared at the 2014 UEFA Under-19 Championship, as the team was eliminated in the semi-final by Portugal after penalties. He missed Serbia’s last spot-kick in the penalty shoot-out. The following summer, Milinković-Savić was one of Serbia’s most influential players at the 2015 FIFA U-20 World Cup, as the team won the tournament. He appeared in six out of seven games and scored one goal against Mali in the group stage. Due to his performances during the tournament, Milinković-Savić was awarded the Bronze Ball. In the summer of 2017, Lazio prevented Milinković-Savić from playing at the 2017 UEFA European Under-21 Championship. In October 2015, Milinković-Savić received his first call-up to the full squad by manager Radovan Ćurčić for Serbia’s UEFA Euro 2016 qualifiers against Albania and Portugal. He remained an unused substitute in both games. In May 2016, Milinković-Savić was selected by newly appointed manager Slavoljub Muslin for friendly matches against Cyprus, Israel, and Russia. However, after failing to receive any playing time in the first two games, Milinković-Savić left the team in agreement with Muslin who said that some other players better fit into his tactical formations. On 30 October 2017, it was announced that Serbia caretaker manager Mladen Krstajić included Milinković-Savić in the squad for friendlies against China and South Korea. In June 2018, he was selected in the Serbian squad for the 2018 World Cup, playing all three group stage matches. Milinković-Savić scored his first two senior international goals on 8 October 2020, settling a 2–1 win over Norway in the semi-finals of the Euro 2020 qualifying play-off. In November, 2022 he was selected in Serbia’s squad for the 2022 FIFA World Cup in Qatar. He played in all three group stage matches, against Brazil, Cameroon, and Switzerland. He scored a goal in a group stage match match against Cameroon, on assist from Andrija Živković. Serbia finished fourth in the group.