Ayaka Ōnishi is a Japanese voice actress from Izumisano City in Osaka Prefecture, born on August 19. She is affiliated with the talent agency Kenyu Office, where she became a预备所属 (preliminary affiliate) in April 2021 before being promoted to准所属 (associate membership) in April 2025. Standing 164 cm tall with AB blood type, she speaks the Kansai dialect, specifically the Senshu dialect.

Ōnishi pursued her passion for voice acting at the Osaka Animation College, a specialized vocational school. Following her graduation, she was accepted as a specially-designated student (tokutaisei) into the talk back training program operated by Kenyu Office in 2020. Her professional skills include the ability to handle her own recording equipment, a talent known as self-recording. Outside of her work, her hobbies include comparing and tasting different types of whisky.

Her professional voice acting career includes a variety of supporting roles in television animation. In 2022, she appeared as a female team manager in the soccer anime Ao Ashi and as Miyuki in MAZICA PARTY. The following year, in 2023, she voiced Ffion Seina in The Dreaming Boy is a Realist and had roles as Mardeia and a witch in Reign of the Seven Spellblades. Her work in 2024 includes appearances as a rookie adventurer in The Strongest Tank's Labyrinth Raids, a child in the long-running series Crayon Shin-chan, and roles in The New Gate.

Ōnishi is particularly recognized for her work in video games. She provides the voice for the character Mejiro Bright in the popular franchise Umayuru: Pretty Gray, also known as Umamusume: Pretty Derby. Her other game credits include roles in Monster Strike, Roppongi Sadistic Night, Card-en-Ciel, and Duel Masters PLAY'S. In addition to animation and games, her body of work includes audio books, drama CDs, narration, and promotional videos.