In youth she spent time in Rome, attending the University of Rome and Bologna before returning permanently to Florence. At the University she received a degree in art history. Her pseudonym derived from "an exceptionally beautiful woman" she knew in her youth. She married art critic Roberto Longhi and in 1950 they founded the journal Paragone. She did several stories and works over the next decades, but she would become best known for a historical novel concerning artist Artemisia Gentileschi. One newspaper even headlined their report of Banti's death by saying Addio, Artemisia. This work revived interest in Artemesia's work and life.
Banti's autobiographical work, Un Grido Lacerante, was published in 1981 and won the Antonio Feltrinelli prize. As well as being a successful author, Banti is recognized as a literary, cinematic, and art critic. After the death of Banti’s husband she replaced him as the director of the art review Paragone.