Kim made his mixed martial arts debut at the Hero's 1 event on March 26, 2005 against kickboxer and mixed martial artist Bob Sapp. Despite a promising start wherein Kim negated Sapp's charging attacks and dealt him a facial laceration that necessitated a medical time-out, Sapp struck Kim in the face immediately after the match resumed and knocked him out. At Hero's 2 in the following July, Kim met kickboxer Ray Sefo in a longer but ultimately similar fight wherein Sefo first stunned Kim with strikes before finishing him with a kick to the head. Kim's subsequent bout in the following November against pro wrestler Sean O'Haire and seasoned fighter Yoshihisa Yamamoto in March 2006 proved more fruitful, allowing Kim to utilize his grappling expertise and defeat both opponents by submission. This was followed by a string of losses against increasingly imposing opponents over the following 15 months. Semmy Schilt escaped Kim's forearm choke and trapped him in a guard before punching him into submission. Don Frye and Mighty Mo knocked him out with strikes. In arguably Kim's most famous match, he replaced Choi Hong-man on short notice to face pro wrestler Brock Lesnar in the latter's debut fight, wherein he submitted to Lesnar's punches after being taken down. At Hero's 2007 in Korea in October, Kim secured the third victory of his MMA career in an openweight bout against Ikuhisa Minowa, winning by technical knockout with a series of punches. His final fight took place about two years later on November 27, 2009 at The Khan 2, where he was knocked out by former sumo wrestlerSentoryū Henri. His record stands at 3 wins and 7 losses.
Kickboxing
Kim made his kickboxing debut on March 3, 2006 at the K-1 World Grand Prix 2006 in Seoul tournament. In his quarterfinal match, he met South Korean sumo wrestler Kim Kyoung-Suk. The bout was unorthodox, with both fighters employing spins and jumping kicks and the much larger Kyoung-Suk chasing Min-soo across the ring. At one point, the judoka slipped while attempting a kick and the rikishi made as though to stomp him, resulting in a point deduction for unsportsmanlike conduct. The penalty gave Min-soo the advantage and he earned a unanimous decision victory. In the following round, Kim met seasoned Muay Thai champion Mourad Bouzidi. Despite Bouzidi's superior technique and powerful low kicks, Kim displayed greater aggression and upper body strength, resulting in both fighters scoring a knockdown apiece and meeting after the initial three rounds for an additional three minutes. After enduring a low blow, Kim finished strongly and was able to move on to the finals against Yusuke Fujimoto. The Japanese karateka struck with low kicks, working on Kim's already-battered legs until he limped. Eventually, Kim fell to Fujimoto's punching combinations in the second round for a knockout loss. Kim fought twice more for K-1, ending his kickboxing career with a 4–1 record following a win over American Scott Junk at the K-1 World Grand Prix 2008 in Hawaii on September 8.
