Born in Tokyo, Hayami's interest in becoming a voice Actress began when she was in elementary school. In 2004, when she was in middle school, she attended junior voice actor classes of Nihon Narration Engi Kenkyūjo, a voice acting training school. Her career began when she passed an audition for I'm Enterprise in 2006, at the end of her second year in training school. Her voice acting debut was in the Indian Summer drama CD. In 2007, she made her anime debut and landed her first major role as Momoka Kawakabe, the main heroine in Touka Gettan. Since then, she has been active in voicing many other characters in anime-related media and other voice acting works. She placed #2 in 2015 Newtype x Machi Asobi Anime Awards for Best Voice Actress while her character Yukino Yukinoshita won Best Female Character Award. She's been hosting her own radio show Hayami Saori no Free Style since 2011 which won Best Comfort Radio in general category at 3rd Aniradi Awards in 2017.

Hayami is known for her singing mainly through her work performing anime and character theme songs, such as Kaede Takagaki in The Idolmaster Cinderella Girls francise. Her debut single, "Yasashii Kibou" (やさしい希望, lit. "Bright Hopes") was released on August 12, 2015. She wrote the lyrics for all the songs in the single. The title song was used as opening theme for anime television Akagami no Shirayukihime in which she also voices the main character Shirayuki. Her second single is a double A-side single "Installation/Sono Koe ga Chizu ni Naru" (その声が地図になる, lit. "The Voice Will Become A Map") was released on February 3, 2015. She also took part in writing and composing both songs. The song "Sono Koe ga Chizu ni Naru" is used as opening theme for the second season of Akagami no Shirayukihime. Her first album Live Love Laugh was released on May 25, 2016. She then released a mini album live for LIVE bundled Limited Edition Live Blu-ray/DVD and CD from her first Japanese concert tour Live Love Laugh on December 21, 2016.