After being kicked off the wrestling team at Hofstra University, Hieron began dealing drugs before being charged with a felony. He turned to
boxing to let his aggressions out on the bags. Finding this to be a good stress-reliever, and with the encouragement of some friends who trained in MMA, Hieron combined his
wrestling skills and burgeoning boxing prowess into a professional MMA career.
Early career In March 2006, Hieron won the Lockdown in Paradise in
Lahaina, Hawaii, and in June 2006 won his IFL debut at the IFL Team Championships in Atlantic City, New Jersey. Following the demise of the
International Fight League due to financial concerns, Hieron signed with Affliction in August 2008. However, that promotion soon folded as well, so Hieron signed with Strikeforce.
Strikeforce Hieron's first Strikeforce fight was set to be against fellow former Zuffa competitor
Nick Diaz at
Strikeforce: Carano vs. Cyborg for the inaugural
Strikeforce welterweight title. However, Diaz missed a pre-fight drug test mandated by the California State Athletic Commission and was denied a license to compete.
Jesse Taylor was named to replace Diaz and the fight was changed to a non-title bout. Hieron won by unanimous decision. He had his heart set on a title shot against Nick Diaz, but has stated that he would be comfortable fighting any top level opponent, as long as the fight, and name is helping him move forward in his career. Hieron faced
Joe Riggs on January 30, 2010 at
Strikeforce: Miami. Hieron won the fight via unanimous decision. After the fight had finished, Hieron's contract with Strikeforce was completed, prompting Hieron to immediately call for demands should he sign a new one. The demands included a shot at champion
Nick Diaz and guaranteed television spots.
Bellator Fighting Championships Hieron and Explosion Entertainment were unable to come to terms, so Hieron instead ended up signing to fight on
Bellator Fighting Championships in the promotion's Season 4 welterweight tournament. In the opening quarterfinal round Hieron won via controversial stoppage when referee Josh Rosenthal stopped the bout when Lapsley did not respond to a hand check. Lapsley contested he wasn't out and this appeared to be the case, but given the position, it is unlikely that he would have survived the round. Hieron stated in a post-fight interview that Lapsley was gurgling and he felt him going out. Hieron won a controversial unanimous decision victory over
Brent Weedman at
Bellator 40 to move on to the tournament finals. At
Bellator 43 Hieron defeated
Rick Hawn via split decision to win the Season 4 Welterweight Tournament. With this victory Hieron earned a title shot against Bellator Welterweight Champion
Ben Askren. Askren defeated Hieron via controversial split decision.
Ultimate Fighting Championship Hieron was expected to face
Jake Ellenberger in a rematch on September 1, 2012 at
UFC 151, replacing an injured
Josh Koscheck. However, after the UFC 151 event was cancelled, Ellenberger/Hieron took place on October 5, 2012 at
UFC on FX 5. Hieron lost via unanimous decision. Hieron was expected to face
Erick Silva on February 2, 2013 at
UFC 156. However, Silva pulled out of the bout citing an injury and was replaced by promotional newcomer
Tyron Woodley. He lost the fight KO (punches) in round 1 and was subsequently released from the promotion. On March 7, 2014, Hieron announced his retirement from MMA competition. ==Championships and accomplishments==