Mark "Boots" Holst fights out of Ottawa, Ontario. Mark received his Muay Thai "Kru" status while training out of OAMA(Ottawa Academy of Mixed Martial Arts), and garnered the nickname "Boots" for his lethal leg kicks. Mark also holds a purple belt under the tutelage of OAMA's head instructor and Renzo Gracie black belt, Pat Colligan. Mark is also a mauy thai instructor at OAMA, and has garnered attention from well-known Muay Thai publications like "Muay Thaimes Magazine".

Holst began fighting professionally in 2006, where he found success fighting in the local Quebec and Ontario MMA circuit. After a Kimura victory over TUF/UFC vet Corey Hill, Holst received the call from the UFC to fight John Gunderson (on short notice). While Holst was on the receiving end of a one-sided fight, the UFC offered him another fight against now lightweight contender, Paul Sass. Although Holst held the substantial edge in striking skills, Sass was able to get the fight to the ground and submit Holst in the first round with a Triangle choke. Following his two fight winless streak in the UFC, Holst was subsequently released.

A few months later, Holst was back fighting on the Quebec MMA circuit, with a match against striking specialist, Markhaile Wedderburn. Holst managed to win the fight with a Rear-Naked choke, but suffered from a Boxer's Fracture from the fight. As such, Holst publicized his retirement from MMA to focus on training and starting his own MMA school with his coach Pat Cooligan. After a year of retirement, Holst returned to the cage to fight Stephane Lamarche where he won in by-way-of Kimura, mid-way through the second round.  Following his successful return, Holst took a fight against BJJ specialist, Leo Santos (who held a flying armbar victory over UFC Welterweight Champion, George St.Pierre at Grappler's Quest). Unfortunatley, Santos was able to expose Holst's main wekness, and submitted the Canadian Muay Thai specialist in the first round with an arm triangle.