Keiichirō Yamamoto is a Japanese voice actor born on December 12 and a native of Ibaraki Prefecture. He is affiliated with the talent agency Aoni Production, having graduated from the agency's training school, the Aoni Juku Tokyo School, as part of its 19th class. His career in the voice acting industry began in the late 1990s, with one of his earliest known anime roles being an operator in the 1999 series Blue Gender.

Yamamoto has built a prolific career, largely defined by supporting roles and character voices in numerous long-running and popular series. Since 2000, he has been a part of the cast for One Piece, voicing various characters including the roles of Ootori, Very Good, and Noazett. His work in the early 2000s also includes notable parts in Vandread: The Second Stage, the CLANNAD ~After Story~ franchise as Tajima, and as Nemuta Masamu in Yo bête! Tobidete! Akubi-chan.

As specified, Yamamoto is recognized for the role of Iori Kōhei in the 2014 series La Corda d'Oro Blue Sky, an adaptation of the romance visual novel. That same year, he also voiced the character Black Knight Geborg in the anime Oreca Battle. Beyond these roles, his extensive anime credits include appearances in major franchises such as GeGeGe no Kitaro (the fifth series), Mononoke, Bobobo-bo Bo-bobo, and a supporting role as Notti Conga in Valkyria Chronicles.

One of the most significant and long-standing aspects of Yamamoto's career is his work in video games, particularly within the hack-and-slash Dynasty Warriors series by Koei Tecmo. He has been the voice of the formidable warrior Xu Huang across numerous titles in the franchise. His portrayal began with Shin Sangokumusou 2 (known as Dynasty Warriors 3) in 2001 and has continued for over two decades, appearing in Shin Sangokumusou 3 through 8, the Warriors Orochi crossover series, and the 2025 release, Dynasty Warriors: Origins. This role represents a major recurring collaboration within the industry.

Other notable video game appearances include roles in the Kamen Rider: Climax Heroes series, Persona 5, Digimon Story: Cyber Sleuth as BanchoLeomon, The Legend of Heroes: Trails from Zero as Harold Hayworth, and Saint Seiya: Sanctuary Battle. He has also contributed to Japanese dubbing for foreign films and provided narration for various television programs. His career is marked by consistent work and versatility, maintaining a steady presence in anime, video games, and television narration for over twenty-five years.