Early career Hirota made his professional debut for Shooto, winning his first two fights by TKO and then won his next four fights all by unanimous decision to reach an undefeated professional record of 6–0. Hirota then faced
Takashi Nakakura for the newly vacated
Shooto Pacific Rim Welterweight Championship. Hirota was handed his first professional loss via unanimous decision and then lost his next fight, also by unanimous decision. Hirota then signed with
Cage Force, and in his debut, knocked out his opponent 16 seconds into the fight before getting another win via TKO. In his next fight in April 2008, at
Cage Force 6, Hirota defeated
Tomonari Kanomata to win the Cage Force Lightweight Championship.
Sengoku Hirota then entered the
Sengoku 2008 Lightweight Grand Prix where he won his first-round fight by knocking out the last
IFL Lightweight Champion,
Ryan Schultz, at
Sengoku 4 in August 2008. He was then eliminated from the tournament in the semi-finals after losing by unanimous decision against
Kazunori Yokota at
World Victory Road Presents: Sengoku 6 in November the same year. In February 2009 he defended his Cage Force title when he fought to a draw with multiple-time
King of Pancrase, Katsuya Inoue, and in May 2009 he defeated PRIDE veteran
Mitsuhiro Ishida by
knockout at
Shooto Tradition Final. had to defend multiple submission-attempts by Kitaoka during the first round, but came back in the second landing strikes on the feet while stopping Kitaoka's takedown-attempts. In the third, Kitaoka was able to take Hirota down and control him on the ground eventually resulting in a yellow-card inactivity-warning for Hirota as he did not improve his position. On March 7, 2010, Hirota announced during
Sengoku 12 that he would be vacating his belt due to his injuries sustained at
Dynamite!! 2009.
DEEP A year after he officially vacated his
Sengoku Lightweight Championship belt, Hirota began fighting for
DEEP. Hirota's debut for the organization was against
Katsunori Kikuno for the
DEEP Lightweight Championship and Hirota won via unanimous decision, and then defended his belt against
Seichi Ikemoto, winning again via unanimous decision. Hirota then vacated his title in April 2012.
Strikeforce On May 29, 2012, it was announced that Hirota would make his United States debut for Strikeforce in July 2012 against
Pat Healy. In a back and forth bout, Hirota showcased technical boxing and some take down defense, but Healy was able to land more during the clinch. Hirota lost the close battle by unanimous decision (30-27, 29–28, 29–28). Strikeforce commentator and former
UFC Middleweight Champion Pat Miletich stated the decision was affected by the home town favoring their own fighter. Hirota was next scheduled to face
Jorge Gurgel on September 29, 2012, but the event was cancelled before the company ceased operations. Hirota was signed along with many other Strikeforce competitors to compete in the UFC.
Ultimate Fighting Championship Hirota faced
Rani Yahya on March 3, 2013, at
UFC on Fuel TV 8. The fight was Hirota's first fight as a
Featherweight. After losing the first two rounds, Hiroto was able to keep the fight standing in the third, but it was not enough under the scorecard and he lost his debut via unanimous decision. In his second UFC fight, Hirota faced
Rodrigo Damm at
UFC on Fuel TV: Nogueira vs. Werdum on June 8, 2013. He lost the back-and-forth fight via split decision and was subsequently released from the promotion following the loss.
Road to UFC: Japan In June 2015, Hirota was announced as one of the eight featherweights competing on
Road to UFC: Japan, a show in the style of
The Ultimate Fighter. On the show he faced Nobumitsu Osawa in the quarter-finals and won by decision. He then faced
Daiki Hata in the semifinals and again won by decision. Hirota ultimately faced
Teruto Ishihara in the finals at
UFC Fight Night 75. Post-fight the UFC announced that Hirota and Ishihara would both be awarded contracts. Hirota was expected to face
Cole Miller on October 15, 2016, at
UFC Fight Night 97. However, the promotion announced on October 6 that they had cancelled the event entirely. In turn, the fight was rescheduled and eventually took place on December 17, 2016, at
UFC on Fox 22 Hirota won the bout by unanimous decision. Mizuto Hirota faced
Alexander Volkanovski on June 10, 2017, at
UFC Fight Night 110. He lost the fight by unanimous decision. Hirota was expected to face
Charles Rosa on September 23, 2017, at
UFC Fight Night 117. After struggling with the weigh-in, Hirota was forced to pull from the event due to health concerns. He was deemed unfit to compete by the UFC medical team. Hirota faced
Ross Pearson in a lightweight bout on February 11, 2018, at
UFC 221. He lost the fight via unanimous decision. Hirota faced
Christos Giagos on December 2, 2018, at
UFC Fight Night 142. He lost the fight via unanimous decision.
Rizin After being released from the UFC after three straight losses, Hirota signed with
Rizin Fighting Federation and faced
Roberto de Souza at
Rizin 17 on July 28, 2019. He lost the bout in the first round via knockout. ==Championships and accomplishments==