Omigawa made his professional mixed martial arts debut in 2005 against future UFC veteran
Aaron Riley at
PRIDE Bushido 7. Omigawa and Riley traded punches before Omigawa was knocked out by a head kick six minutes into the first round. Omigawa then fought for the British
Cage Rage organization against future two-time
K-1 HERO'S Middleweight Champion Gesias Calvacante. He again lost this fight by knockout, this time from an overhand right. After a majority decision loss to
Kazunori Yokota brought Omigawa's record to 1-4, he then strung together three consecutive wins in the DEEP organization, before making his UFC debut at
UFC 76 against
Matt Wiman. He lost this fight via unanimous decision. Omigawa then fought again for the UFC at
UFC Fight Night: Swick vs Burkman against
Thiago Tavares and lost again via unanimous decision. After cutting down to the
Featherweight division, Omigawa's recognition and career began to take off. Though he lost his division debut against future
WEC and UFC veteran
Jung Chan-Sung, Omigawa made a resurgence when he entered the
Sengoku Featherweight Grand Prix tournament promoted by
World Victory Road. As a heavy
underdog he defeated the likes of
LC Davis via unanimous decision and
Nam Phan via
TKO. In the semi-final he faced then-undefeated
Pancrase Featherweight Champion and future
Sengoku Featherweight Champion Marlon Sandro. This fight was originally ruled as a majority draw before Omigawa was awarded the victory by split decision. This brought Omigawa to the final of the tournament against
Masanori Kanehara (the semi-finalist loser) who stood in for
Hatsu Hioki as Hioki could not continue to compete. Omigawa lost by a close split decision against Kanehara but in return earned him the recognition as a strong Featherweight. After the tournament Omigawa continued to earn a spot as a world top five Featherweight, defeating the likes of
Hatsu Hioki via a controversial split decision,
Hiroyuki Takaya via TKO at
Dynamite!! 2009, Micah Miller, and
Cole Escovedo via
armbar.
Return to the UFC The 12-8-1 Omigawa re-signed with the UFC in the
Featherweight division and he faced then-undefeated
Chad Mendes on February 5, 2011 at
UFC 126. He lost the fight via unanimous decision. Omigawa was defeated by
Darren Elkins via unanimous decision on June 11, 2011 at
UFC 131. The decision was considered controversial, and despite the loss, UFC president
Dana White stated on his
Twitter account that both fighters would be paid a win bonus. Omigawa faced British fighter
Jason Young on November 5, 2011 at
UFC 138 and won the fight via unanimous decision. Omigawa next faced former
Jungle Fight Lightweight Champion Yuri Alcântara on January 14, 2012 at
UFC 142. Omigawa lost the fight via unanimous decision. Omigawa fought fellow judoka
Manny Gamburyan on August 4, 2012 at
UFC on FOX 4. He lost via unanimous decision. After back-to-back losses in the UFC, Omigawa was released from the promotion yet again.
Post-UFC Omigawa fought at DREAM 18 against
Tatsuya Kawajiri on
New Year's Eve 2012. Omigawa lost via unanimous decision. The loss puts Omigawa at 1-6 in his last seven fights, all of which have gone to a decision.
Road FC In May 2013, it was announced that Omigawa had signed with Korea's
ROAD FC and would debut against fellow judo practitioner, Bae Young Kwon at Road FC 12. After a back and forth fight, Omigawa lost a controversial decision.
Shootboxing Bringing his boxing and judo skills to the kickboxing/grappling hybrid sport of
shootboxing, Omigawa entered the 2013 –65 kg S-Cup held at
Shoot Boxing Battle Summit Ground Zero Tokyo 2013 in Tokyo, Japan on November 15, 2013. After defeating Yuki Hiroshi Kimaya by unanimous decision in the quarter-finals, he then faced fellow mixed martial artist
"Wicky" Akiyo Nishiura in the semis. The fight was ruled a majority draw after the regulation three rounds and so went to an extension round to produce a winner, after which Omigawa was given the nod by all three judges. In the tournament final, he fell victim to a
flying knee from Hiroaki Suzuki, losing by knockout in round two.
Retirement Bout After winning the next 6 bouts after his loss in Road FC, mostly fighting under the banner of
DEEP, Omigawa announced that he would be facing
Daisuke Nakamura in his retirement bout at DEEP 106 on February 26, 2022. He lost the bout the fight via armbar in the third and retired afterwards. ==Championships and accomplishments==