Miyahara debuted as a voice actress in 1998 as Shouko Yamanobe in Mamotte Shugogetten.
Notable roles she has played include Momoko Asuka and Masaru Yada from the Ojamajo Doremi series, Wallace from Digimon Adventure 02, Miyako Gōtokuji/Rolling Bubbles from Powerpuff Girls Z, Lyuze from Casshern Sins, and Akari Tsukumo from Yu-Gi-Oh!
In addition to her voice acting, Miyahara also pursued a singing career and released her first extended play, Reason, in 2003.
When Miyahara was in junior high, she and her family moved to Austria, where she attended an international school and learned English.
Miyahara also lent her vocals to some of Genki Rockets' songs as part of fictional space girl Lumi's image.