Kitaoka is a Lightweight and has fought most of his career in Pancrase but has also fought in Dream, Deep, and Sengoku. He is a black belt in Brazilian Jiu Jitsu and a black belt in Judo. He has beaten notable fighters in Kurt Pellegrino, Carlos Condit, Paul Daley, Kazunori Yokota, Eiji Mitsuoka, Takanori Gomi, Jutaro Nakao, and Katsunori Kikuno. He was the first Sengoku Lightweight champion and won the 2008 Sengoku Lightweight Grand Prix. Kitaoka is regarded as one of the lightweight division's best grapplers..

Kitaoka challenged for the Lightweight belt at Deep: 62 Impact against champion Daisuke Nakamura. Kitaoka won by decision to claim the Lightweight title.

Kitaoka's next fight would be a non-title affair against Dom O'Grady at Pancrase 252: 20th Anniversary on Spet 29, 2013. Kitaoka would dominate the bout, ending it via guillotine choke just over one minute into the opening round. 

Kitaoka would lose his next fight however, getting knocked out by Ramazan Esenbaev at Inoki Bom-Ba-Ye 2013 on December 31, 2013. 

2014 would prove to be a great year for Kitaoka as he would go 3-0 for the year. He first win came in a defense of his DEEP Lightweight title against Naoto Miyazaki at DEEP: 66 Impact on on April 29, 2014. Kitaoka would win the fight via unanimous decision. He would win his second fight of the year via unanimous decision over Richie Whitson at Pancrase: 261 on October 5, 2014. Kitaoka would then close out a perfect 2014 by beating Yoshiyuki Yoshida via unanimous decision at DEEP-DREAM Impact 2014: Omisoka Special on December 31, 2014.

Kitoaka would increase his winning streak to four fights when he won his opening fight of 2015, handing Akira Okada a unanimous decision loss at Pancrase: 265 on March 15, 2015.