 In professional kickboxing, McCullough has competed for K-1.McCullough began his mixed martial arts career with a first-round TKO victory at the Palace Casino in Lemoore, California, in 2001.Between 2003 and 2007, "Razor Rob" went 10-1 with nine stoppage victories and only a split-decision loss to Harris Sarmiento, which he later avenged.