On March 2, 2008, he took part in a Big Brother (Poland) show.
On April 2, 2008, he was knocked out in the second round by Andrzej Wawrzyk in a boxing bout for the polish heavyweight championship.
On November 29, 2008 Najman defeated Slovakian heavyweight boxer Anton Lascek.
Najman signed a four-fight MMA contract in 2009 with KSW. Due to injury, his debut fight in KSW XI against Jahmai Satisch on May 12 was cancelled. He made his debut against a fellow newcomer to the sport, the only five time World's Strongest Man title holder Mariusz Pudzianowski on December 11, 2009 at KSW XII. In the 1st round Marcin was submitted by a series of punches and kicks, being knocked to the canvas. Najman will compete in summer 2010.