Kekilli's breakthrough role came in 2004 with Fatih Akin's critically acclaimed film "Head-On." The movie tells the story of two young Turkish immigrants in Germany who engage in a passionate and tumultuous relationship. Kekilli's portrayal of Sibel, the female lead, earned her widespread recognition and critical acclaim. The film won several awards, including the German Film Award for Best Film and the European Film Award for Best Film.