While a sophomore in high school, Amamiya was introduced to a video collection of roles of voice actress Miyuki Sawashiro. Following this, Amamiya decided to become a voice actress.
Amamiya, together with Momo Asakura and Shiina Natsukawa, passed an audition held by Music Ray'n in 2011, with the three making their voice acting debut in 2012. Her first lead role was Kaori Fujiyama in the 2014 anime television series One Week Friends, where she also performed the series' ending theme "Kanade" (奏（かなで）?, lit. "Symphony"), a cover of a 2004 single by Sukima Switch. She also played the role of Akame in the anime television series Akame ga Kill which premiered in July 2014. She made her official music debut for Music Ray'n by performing Akame ga Kill 's opening theme "Skyreach". In late 2014, Amamiya, Asakura, and Natsukawa formed the music unit TrySail., which released its first single "Youthful Dreamer", used as the opening theme to the anime television series Ultimate Otaku Teacher, on May 13, 2015.
Amamiya, together with Reina Ueda and Aya Suzaki, received the Best New Actress award at the 9th Seiyu Awards in March 2015.