In 2023, he joined Danish side OB, and spent the first half of 2024 on loan at Polish club Śląsk Wrocław.
Mustafić started playing football at his hometown club Sloboda Tuzla, before joining Sarajevo's youth academy in 2015.
[4] In January 2020, Mustafić was loaned to Slovak side Slovan Bratislava until the end of season, with an option to make the transfer permanent, which was activated in July.
[5] On 12 January 2024, after spending the previous year with Danish side OB, Mustafić joined Polish club Śląsk Wrocław on loan until the end of the season.
[8] Mustafić was a member of Bosnia and Herzegovina under-19 team under coach Toni Karačić.