Born in Rome, Italy, she is the daughter of former Bond girl Barbara Bach and businessman Count Augusto Gregorini. Her mother is of Jewish and Irish descent. Gregorini is also the stepdaughter of Beatles Drummer Ringo Starr, with whom she is close. After boarding at The Moses Brown School, she attended Brown University graduating in 1990.
She contributed two songs to the Soundtrack of the minor film See Jane Run (2001), in which she also had a small acting role. She worked as a musician with her first CD "Sequel" (2003), where she sings, and plays the guitar and bass.
Gregorini sold scripts to both HBO and Paramount Pictures before co-helming, with Princess Tatiana von Fürstenberg, her directorial debut Tanner Hall, a coming of age story set in an all-girls boarding school in Rhode Island. Gregorini and von Furstenberg also co-wrote the independent film, loosely based on their own adolescent experiences. Gregorini said in an interview, "Naturally there are some autobiographical elements, combined with things we'd witness in boarding school, and many other parts that we made up completely. You will certainly find characteristics of both of us in each of the four main girls and if you spend even a half-hour with us, it will be very apparent to you, which girls are most like me and which ones are most like Tatiana." The film was an official selection at the 2009 Toronto International Film Festival.
Her film The Truth About Emanuel—starring Jessica Biel, Kaya Scodelario and Alfred Molina—was selected for the US dramatic competition at the 2013 Sundance Film Festival.