Knox was signed to World Wrestling Entertainment in February 2005, and made a handful of appearances on WWE shows, including one appearance as a masked "jihadist" for Muhammad Hassan, in the infamous segment that led to Hassan's ousting from WWE.
Knox debuted on the June 20, 2006 episode of ECW as a heel by interfering in Kelly Kelly's striptease segment, coming from the backstage area and covering her with a towel before escorting her off stage, though he was unnamed on-screen at the time. It was later revealed that Kelly was Knox's on-screen girlfriend, and he informed her that he did not appreciate her stripping in front of anyone but him. For his in-ring debut, a win over Danny Doring, Kelly accompanied him to the ringside acting as a valet. Knox was pushed strongly, interfering in matches, and squashing his opponents. He later formed a short-lived tag team with Test before starting a feud with CM Punk, after growing jealous of Kelly Kelly's admiration towards Punk. CM Punk won every match in the feud, including a qualifying match for December to Dismember's Elimination Chamber match.
Knox made his pay-per-view debut at Survivor Series where he teamed up with Rated-RKO, but was the first man eliminated after taking a superkick from Shawn Michaels. Upon his elimination, he was subsequently mocked by D-Generation X, as he was virtually unknown compared to the other participants. His next pay-per-view appearance saw him abandon Kelly Kelly during a mixed tag team match against Kevin Thorn and Ariel at December to Dismember, resulting in his team's loss. He then attacked her on the next ECW episode, breaking the duo up for good.
After being taken off television, Knox returned on February 13, 2007 episode ECW, where he lost easily to CM Punk. Knox was again taken off television for several months.
Knox returned on the September 11 episode of ECW, defeating Balls Mahoney. The next week, he lost in a rematch to Mahoney. He then easily defeated Nunzio the week after. The next week Knox wrestled against ECW Champion CM Punk, again losing to Punk after a Go To Sleep from Punk. After months without any notable storylines, he began a feud with Tommy Dreamer whom he defeated in a series of matches, including an Extreme Rules match on the 100th episode of ECW. He then began a feud with Finlay. After weeks of confrontations between the two, they finally had a match on the September 26 edition of ECW, where they had an ECW Championship scramble qualifying match, which was won by Finlay.
On the October 27 and November 3, 2008 episodes of Raw, two vignettes were aired to promote his arrival on the brand. His look drastically changed as well from his previous clean cut look to long unkempt hair and a long beard. He debuted the following week, on November 10, defeating D-Lo Brown. He attacked Rey Mysterio two times over a period of three weeks. After losing to Mysterio, Knox attacked Rey once again. Interviewer Todd Grisham, asked Knox why he attacked Rey Mysterio and he answered saying he did not know why. In a house show at Cape Girardeau, Missouri, Knox won a battle royal to become an entrant at the World Heavyweight Championship Elimination Chamber match at No Way Out. At the event, he was eliminated by Chris Jericho and was the second competitor eliminated overall.
On April 15, Knox was drafted to the SmackDown brand as part of the 2009 Supplemental Draft. He made his debut for the brand on the May 8, 2009 episode of SmackDown, defeating R-Truth in a singles match. This was his last win on Smackdown as after that he occasionally competed on Smackdown and WWE Superstars, always putting over other talent. On the August 14 episode of SmackDown, Knox debuted new elements to his character that included knowledge of biology and the human anatomy, using this knowledge to methodically inflict pain upon his opponents. His final PPV appearance was at Wrestlemania XXVI, where Knox competed in a 26 man Battle Royal (a dark match) and was one of the final four men. Knox's final match was a loss to JTG on the April 23, 2010 edition of SmackDown, on the same day WWE announced that Knox had been released from his contract.