Seferi was born in Gostivar, SFR Yugoslavia (present-day North Macedonia) and is of Albanian heritage. Whilst in Yugoslavia as an eight-year-old he started wrestling, a sport which his grandfather had competed in professionally. In 1992 his family fled from Gostivar and moved to Burgdorf, Switzerland. Seferi found it hard to adapt to the lifestyle and language change, and as he was 15 at the time he was too old for compulsory education. He took up boxing in order to help with integration into Swiss society. He began to train under the guidance of trainer Sandor Konya at a local gym in Burgdorf, but he also trained with legendary Swiss martial artist and kickboxer Andy Hug as well.