Eligible for
Austria,
Bosnia and Herzegovina and
Croatia, Sučić explicitly opted for Croatia, despite interest from the
Austrian Football Association. On 9 March 2021, he was named in
Igor Bišćan's
23-man squad for the group stage of
UEFA Under-21 Euro 2021; however, he was ruled out on 21 March due to an injury and replaced by
Matej Vuk. On 17 May, he was named in Bišćan's
23-man squad for the knockout stage of the tournament; however, the same occurred and he was replaced by
Neven Đurasek on 25 May. During
UEFA Under-21 Euro 2023 qualifiers in September and October 2021, Sučić scored three goals and assisted once in three games, prompting
Zlatko Dalić to call him up to the senior team on 9 October, two days ahead of a
World Cup qualifier against
Slovakia, due to
Mateo Kovačić's suspension. He made his senior debut in the said qualifier, which ended as a 2–2 draw. On 9 November 2022, Sučić was named in Dalić's
26-man squad for the
2022 FIFA World Cup, where he remained an unused substitute as Croatia finished third. Due to the recovery process from knee surgery he underwent in March 2023, Sučić was omitted from
Croatia's 23-man squad for the
2023 UEFA Nations League Finals. On 20 May 2024, Sučić was named in Dalić's preliminary 35-man squad for
UEFA Euro 2024; on 7 June 2024, he made it to the
final 26. At the tournament, he played in all three matches, as Croatia finished their campaign already in the
group stage. In May 2025, Sučić was called up for Croatia's
2026 FIFA World Cup qualifiers against
Gibraltar and
Czechia, played on 6 June and 9 June, respectively. Ahead of the Czechia game, Sučić left the national team's camp to attend his sister's wedding in
Uskoplje, allegedly angering Dalić. Dalić refrained from commenting on the issue in public. When Dalić announced the list of players for the September matches against the
Faroe Islands and
Montenegro, it was apparent that Sučić was not called-up. Dalić denied that Sučić was "either written off, or punished, or chased away" at a press conference ahead of the Faroe Islands game. However, Sučić did receive an additional call-up before the October matches against Czechia and Gibraltar. On 12 October, in a 3–0 victory against the latter opponent, he scored his first goal for the national team. ==Personal life==