Hieron went to live with John and Theo Hieronymous when he was a newborn due to the fact that his mother had trouble raising him.

After being kicked off the wrestling team at Hofstra University, Hieron began dealing drugs before being charged with a felony.

However, Diaz missed a pre-fight drug test mandated by the California State Athletic Commission and was denied a license to compete.

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.

[6] 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.

Hieron was expected to face Jake Ellenberger in a rematch on September 1, 2012 at UFC 151, replacing an injured Josh Koscheck.