Youth Fahim won the golden boot in the
2017 SAFF U-15 Championship as he finished top scorer with 6 goals out of 4 matches. His goals included a hat-trick against
Sri Lanka U15 and he also managed to score in both games against
Bhutan U15 one of which came during a 8-0 trashing. He was in the scoresheet again in the semi-finals against
Nepal U15 as Bangladesh lost 4–2 and were knocked out of the competition. On 24 September 2017, Fahim scored a long-range winner against the
Qatar U16 team and sealed a stunning 2–0 win for Bangladesh during the
2018 AFC U-16 Championship qualifiers. In the end, even though Bangladesh failed to qualify for the main tournament, the victory was seen as a huge achievement and attracted the attention of local media. Fahim was the joint top scorer in the
2019 SAFF U-18 Championship alongside his teammate Tanvir Hossain and
Gurkirat Singh from
India U18. His goals came against
Sri Lanka U18 in the group stages and
Bhutan U18 during the semi-finals of the tournament. He was also in the squad during a disappointing
2020 AFC U-19 Championship qualification campaign. In 2019, he also participated in the U19 Three Nations Tournament, hosted by
Qatar FA. Fahim was named on the
Bangladesh U23 team by coach
Maruful Haque for the
AFC U-23 Championship 2022 qualifiers. He managed to play in all of the 3 games, the
qualifiers ended with Bangladesh failing to score a single time. Although the poor performances shown by the team, Fahim was impressive during the games, with his quick feet and dribbling, which earned him a
Bangladesh national team call up.
Senior In 2020, Fahim was called up to the national team for the first time during the Bangabandhu Gold Cup. Although he was named on the final squad list, he did not participate in any of the games. He was called up once again, this time for the
2018 FIFA World Cup qualifiers in June 2021, bu failed to join the team in the end due to passport complications. He was also named in
Jamie Day's 35-man preliminary squad for the
2021 SAFF Championship, however, his name was cut off when interim coach
Óscar Bruzón named his final squad. On 13 November 2021, Fahim finally made his debut for the
Bangladesh national team coming on as a substitute for
Mohammad Ibrahim during the start of the second half against
Maldives in the
2021 Four Nations Football Tournament. Bangladesh won the game 2–1 which was their first victory against
Maldives in 18 years. He was included in the final squad for the
2023 SAFF Championship. On 22 June 2023, Fahim squandered a one on one goal scoring opportunity against the Lebanese goalkeeper, to give Bangladesh the lead in the tournament opener against
Lebanon. He came under heavy criticism from local media, after his team went down 0–2. On 17 October 2023, Fahim assisted the opening goal and scored the winner against Maldives in the second leg of the
2026 FIFA World Cup qualification – AFC first round, securing Bangladesh a 3–2 aggregate victory and a place in the
second round. ==Career statistics==