Tatsuya Kawajiri (born May 8, 1978) is a Japanese mixed martial arts fighter and a former Shooto welterweight champion, currently competing in DREAM's lightweight division.

He holds wins over the likes of UFC veteran Yves Edwards, and Vitor Ribeiro whom he captured the Shooto Championship Belt. Kawajiri's Bushido Tournament match with Takanori Gomi was voted as PRIDE Fighting Championship's Fight of the Year.

Kawajiri's professional career started in Japan's Shooto organization where he lost to Takumi Nakayama via rear naked choke at 2:44 of the first round. After this loss Kawajiri went on to fight Yohei Suzuki to a Draw at Shooto's "Wanna Shooto 2001."

He would then remain undefeated in Shooto until a disappointing decision loss to future Shooto welterweight champion Vitor Ribeiro in 2002. He would then continue on a new winning streak eventually rematching Ribeiro to capture the welterweight crown at Shooto's 2004 Year-End show.

On 22 May 2005 Kawajiri made his debut in PRIDE and score a quick TKO over In Seok Kim. He went on to score a one-sided victory over Luis Firmino at PRIDE Bushido 8 on July 17, 2005. On 25 September, he entered PRIDE's first ever Lightweight tournament in hopes of eventually being crowned PRIDE's first Lightweight Champion as well as holding the Shooto championship at the same time.

His first match in the tournament was against MMA lightweight superstar Takanori Gomi. Gomi ended up knocking down Kawajiri after a flurry of punches and proceeded to submit him with a rear naked choke 7:42 into the first round.

Kawajiri went back to Shooto to defend his lightweight championship against Joachim Hansen (one of the four people to have ever beaten Gomi). The match was stopped 8 seconds into the first round when Hansen was disqualified for kicking Kawajiri in the groin, making Kawajiri the victor. Kawajiri came back to PRIDE in a fight against Charles Bennett whom he submitted by kneebar after 2:30 in the first round. He then made another PRIDE appearance in which he fought Chris Brennan and scored an even quicker victory 29 seconds in the first round by TKO. His next fight was a non-title bout against Per Eklund in Shooto where he scored a TKO at 4:10 into the first round.

Kawajiri return to PRIDE was at PRIDE Shockwave 2006 on New Years Eve. There he lost a controversial decision to at the time undefeated American fighter and rising star in the lightweight division, Gilbert Melendez.

On January 23, 2007, Tatsuya Kawajiri relinquished his Shooto title because he could not defend his title by the next Shooto event due to a thumb injury that occurred with his fight against Melendez.

In March 2008, Kawajiri entered the DREAM Lightweight Grand Prix, where he has advanced to the semifinals after back to back victories over Kultar Gill, and Brazilian Top Team fighter Luiz Firmino. At DREAM.5 Kawajiri lost a semi-final match-up to Eddie Alvarez by TKO at 7:35 of the first round.