Ultimate Fighting Championship Due to his strong performance in the
Light Heavyweight finals, where he lost a unanimous decision to
Forrest Griffin in a back and forth fight, Bonnar was awarded a six-figure UFC contract along with Griffin. After his loss to Griffin, Bonnar became the staple of the regular
UFC Ultimate Fight Night shows at the
Hard Rock Hotel and Casino in Las Vegas, defeating such notables as
Sam Hoger,
James Irvin and
Keith Jardine before succumbing to
Rashad Evans by majority decision. In 2006 Bonnar lost a unanimous decision against
Forrest Griffin in the long-anticipated rematch at
UFC 62. After UFC 62, Bonnar tested positive for the banned substance
Boldenone, a type of
anabolic steroid. The commission issued a nine-month suspension on Bonnar's fighter's license and fined him $5,000. Bonnar was forced to withdraw from his fight against
Matt Hamill at
UFC Fight Night 13 due to a serious knee injury he suffered during training. He returned to action at
UFC 94 against
Jon Jones, which resulted in a loss via decision. In his next fight at
UFC 100 Bonnar lost a unanimous decision to
Mark Coleman. Bonnar mentioned on the MMA Live Post Fight Show for
UFC 101 that he was considering a drop down to
Middleweight after two disappointing losses at
Light Heavyweight. Despite this, Bonnar next faced
Krzysztof Soszynski on February 21, 2010, at
UFC 110. Soszynski was victorious at 1:04 in the third round, due to TKO (Cut). Video replays that showed that the cut was opened up by a clash of heads led Bonnar to appeal referee
John Sharp's decision. It was announced on March 10 that he had lost the appeal and the result would stand as a TKO win for Soszynski. At UFC 116, Bonnar won the rematch with a second-round TKO against Soszynski after catching him with a knee. The win broke Bonnar's three fight losing streak, bringing his UFC record to 6-6. The fight earned Bonnar and Soszynski
Fight of the Night honors alongside
Yoshihiro Akiyama and
Chris Leben's fight. Bonnar fought
Igor Pokrajac on December 4, 2010, at
The Ultimate Fighter 12 Finale. He won the bout via unanimous decision (29–26, 29–26, and 29–26). Bonnar was expected to face
Karlos Vemola on August 14, 2011, at
UFC on Versus 5. However, Bonnar was forced to withdraw from the bout due to an injury and was replaced by
Ronny Markes. Bonnar faced
Kyle Kingsbury on November 19, 2011, at
UFC 139. Bonnar defeated Kingsbury by unanimous decision (30–27, 30–25, and 30–27). With the UFC needing to replace the main event at
UFC 153, they turned to Bonnar and
Anderson Silva to fill the spot left empty by injuries. The two UFC vets squared off in a
Light Heavyweight match October 13, 2012, in
Rio de Janeiro, Brazil. Silva won the fight via TKO. Bonnar tested positive for anabolic steroids after the fight (
Drostanolone). After his loss to Silva it was announced on October 30, 2012, by UFC president
Dana White that Bonnar had retired from
MMA competition.
UFC Hall of Fame Shortly after the announcement of
Forrest Griffin's retirement, Dana White announced that Bonnar and
Griffin would be inducted into the
UFC Hall of Fame. Bonnar and Griffin were officially inducted on July 6, 2013.
Bellator MMA On August 27, 2014,
Bellator announced they had signed Bonnar to a multi-fight deal, seemingly coming out of retirement. Bonnar faced
Tito Ortiz on November 15, 2014, at
Bellator 131 and lost via split decision. Thereafter, Bonnar retired for a second time. ==Professional wrestling career==