Kenji Yonekura was a flyweight boxer who fought at the 1956 Melbourne Olympics, losing in the quarter-finals. He turned pro in 1958, fighting through 1962, and recording a professional record of 13 wins (1 by KO), 10 losses (3 by KO), and 1 draw.

Yonekura débuted as a pro on 19 August 1958 when he defeated Shichiro Kimura by decision. He twice foughtPascual Pérez, losing both times by unanimous decision, including a bout for the world flyweight title on 10 August 1959. Yonekura also fought for the world bantamweight title on 23 May 1960, losing a split decision to José Becerra.

In 1962 Yonekura won the Oriental and Pacific Boxing Federation Bantamweight title by unanimous decision over Filipino Marcing David. Yonekura retired after losing to Katsutoshi Aoki by decision on October 1962, having lost his final two bouts.