Before the 2019 season, Shahin made the move to BK Häcken.[5] During the 2020 season, he scored 44 goals in 20 games for the under-17s.[6] Shahin also made his Allsvenskan debut in a 3–0 victory against Falkenbergs FF on 3 October 2020, as a substitute in stoppage time.[7] At the end of the season, he signed his first professional team contract with BK Häcken, agreeing on a three-year deal despite interest from several major Premier League clubs.[6]
On 1 September 2021, Shahin was loaned out to AFC Eskilstuna for one year,[8] playing two games in the 2009 Superettan.[9] On 14 February 2022, he was sent on another one-year loan, to Qviding FIF,[10] where he scored 12 goals in 28 games in the Ettan.[9]
Shahin received his first call-up to the Lebanon national team on December 15, 2023, for a training camp in preparation for the 2023 AFC Asian Cup.[14] However, due to paperwork issues, he was not included in the final tournament squad.[15] Shahin's first official call-up was for Lebanon's 2026 FIFA World Cup qualification matches against Australia in March 2024.[15]
^"رادولوفيتش يستدعي 29 لاعباً الى معسكر طرابلس" [RADULOVIC CALLS UP 29 PLAYERS TO THE TRIPOLI CAMP] (in Arabic). The Lebanese Football Association. 16 December 2023. Retrieved 22 December 2023.