Stefania De Peppe is an established Italian voice actor with a career spanning over two decades, known for her versatility in dubbing animation, live-action television, and video games. Her entry into the world of voice acting occurred somewhat by chance early in her career. While working as an actress and model, she was heard by a puppeteer who offered her the voice of a puppet for an Italian television program. This opportunity led her to meet a fellow voice actor who recognized her talent and encouraged her to pursue dubbing professionally. She subsequently trained with Donatella Fanfani at the CDA studio in Italy and has been active in the field for approximately 24 years.

De Peppe has lent her voice to a wide array of characters in animated series and films. In the anime franchise Little Witch Academia, she is the Italian voice of the main protagonist, Atsuko "Akko" Kagari. Her work on this character includes the 2013 short film, the 2015 film Little Witch Academia: The Enchanted Parade, and the 2017 television series. She has described Akko as one of the most challenging roles of her career due to the character's rapid-fire dialogue and frequent, exaggerated emotional shifts which required a specific vocal characterization. Her involvement with the franchise extended beyond performing; she also served as the dubbing director for the Italian adaptations of the Little Witch Academia projects produced by Dream & Dream. Another notable anime role is voicing the character Zoe in the 2020 revival series Topo Gigio. Her work also includes providing voices for the Italian dubs of international animated productions such as Barbie Dreamtopia, Blue's Clues & You!, and the Minions franchise, where she voiced the yellow characters in Minions 2: The Rise of Gru.

While highly active in animation, De Peppe's career is defined by a broad range of live-action and video game roles. She is particularly recognized for her long-running role as Lagertha in the historical drama series Vikings, a character to whom she felt a deep connection over six seasons. She also voiced key characters in critically acclaimed series such as The Handmaid's Tale and The Last of Us, where she played Marlene in the video game adaptation. Her extensive videogame credits further include the female protagonist in Fallout 4, Vanasha in Horizon Zero Dawn, and a role in Destiny.

Throughout her career, De Peppe has demonstrated a commitment to her craft, emphasizing the importance of acting training and technical skill for aspiring voice actors. Outside of her professional work, she is known for her long-standing veganism and animal rights activism, which has influenced her career choices, leading her to decline roles that conflict with her ethical beliefs and to volunteer her voice for animal rights organizations.