Sudo had his debut in Ultimate Fighting Championship at UFC 38, facing Leigh Remedios. Making his entrance in a kimono and a tengu mask, Sudo showed his personal style by dancing and throwing spin kicks to open the match, eventually launching a flying triangle choke attempt which lasted for most of the round. At the second round, Genki threw Remedios with a hip throw and locked a rear naked choke, making him tap out. The Japanese wrestler then posed with a flag of all the nations and proclaimed his catchphrase of "We Are All One" for a crowd pop.