Ünel began as a theatre actor at the Berlin Tacheles where he played the lead and also directed the play "Caligula". Ünel made his film debut in 1988's "The Passenger". He played a private detective in the film "Dealer" which he followed up with a role in Fatih Akin's "Im Juli". He then portrayed the alcoholic Cahit Tomruk in Akin's "Head-On" ("Gegen die Wand"), which won the Golden Bear at the Berlinale 2004 and brought him international recognition. Ünel also won the German film prize for Best Actor for this performance.