グラウベ・フェイトーザ
Overeem had his first professional kickboxing fight at the age of 17, in a K-1 rules fight on , winning the fight. After that he fought against Paul Hordijk, winning by decision on . Overeem then moved on to K-1, having two K-1 fights in six years against Errol Parris and Glaube Feitosa. Overeem was knocked out in both bouts and stayed with MMA from then on. He did not fight in K-1 for four more years.