Started her career as a jazz singer before her acting debut in Federico Fellini's La Dolce Vita (1960). Was remembered particularly for her long friendship with director Pier Paolo Pasolini, after his death, she dedicated herself to preserving his memory and life's work, including poetry and a well-received documentary about him. She had a great disdain for Dagmar Lassander. When Lassander was cast for a major role alongside her in Hatchet for the Honeymoon (1970), she made sure that her role was expended while Lassander's part was shortened. Also, she treated Lassander very derogatory. Decades later, Lassander claimed that Betti was "very rude", but didn't share any details out of deep respect for the older actress. Dubbed the voice of the Demon in the Italian version of The Exorcist (1973). Commander of the French Order of Arts and Letters. [1984].