Isabella Guarnieri is a Brazilian voice actress, born in São Paulo on September 30, 2000. She comes from a family with a strong legacy in dubbing, being the daughter of voice actor Tatá Guarnieri and the sister of Caio Guarnieri, also a dublador. Her great-uncle was the renowned actor and playwright Gianfrancesco Guarnieri.

Guarnieri began her career in voice acting at a young age and has since built an extensive portfolio working on dubbing for animation, live-action series, and films. Her work primarily involves providing Portuguese voices for international productions, making her a familiar voice to Brazilian audiences.

Among her most recognized roles in animation and anime are Himiko Toga in My Hero Academia and Nezuko Kamado in Demon Slayer. She also voiced Yotsuha Miyamizu in the feature film Your Name. and Apple Bloom in My Little Pony: A Amizade É Mágica. Her repertoire includes Sasha in Amphibia and the title character in the animated film Nimona.

In addition to her anime work, Guarnieri has voiced prominent characters in live-action productions. She is known for being the second voice of Arya Stark, originally played by Maisie Williams, in the Brazilian dubbing of the series Game of Thrones. She also voiced Riley Andersen from the Disney Pixar film Inside Out and has been the voice of characters like Zuri Ross in the series Jessie and its spin-off Bunk'd, as well as Sofia in the animated series Princesinha Sofia.

Guarnieri's work extends to video games as well. She voices a young version of the character Pauline in the 2025 Nintendo Switch game Donkey Kong Bananza, marking the first time a game in the franchise has received Portuguese dubbing.