Rio Mamesaki is a Japanese voice actress affiliated with the agency Production Ace. She was born in Tokyo on April 4th. Mamesaki holds qualifications including the Japanese Kanji Proficiency Test Level 3 and the ICT Proficiency Test Level 3. Her special skills include dancing and having a flexible left thumb, and her hobbies include watching comedy and copying dance routines.

Mamesaki's most prominent and defining voice role to date is Joanna Elizabeth Stafford in the television anime series Luminous Witches. This series, a spin-off of the Strike Witches franchise, features a squadron of witches who use music and song to support people rather than engage in combat. Mamesaki was announced as part of the cast in December 2021, taking over the role from Kyō Tachibana, who had gone on hiatus. She performed alongside a large cast of voice actresses who form the musical idol unit within the series.

Consistent with the musical nature of Luminous Witches, Rio Mamesaki's work has been closely tied to the series' music releases. She participated in the opening theme song WONDERFUL WORLD and the ending theme song Watashi to Minna no Uta as part of the Luminous Witches cast. Her voice is featured on multiple character song CDs for the anime, including a duet titled Masshiro Ribbon with her co-star Rino Yoshikita, who plays Sylvie Cariello. These music releases, which include solo and group performances, represent a significant portion of her professional discography. Beyond this major role, no other anime voice acting credits for Rio Mamesaki are currently documented in available sources.