At the age of three, Sumire Morohoshi became part of the Himawari Theatre Group after being captivated by the character Yubaba from Sen to Chihiro no Kamikakushi. Her seiyuu career began at seven years old when she provided her voice for Carrie Sheedy in Red Garden. Additionally, Morohoshi has appeared in several television dramas and lent her talents as young Anna in the Japanese dub of Frozen in 2013.