Fiorentino was born Clorinda Fiorentino in Philadelphia, Pennsylvania. Her father was a steel contractor and her mother, also named Clorinda, was a homemaker. Fiorentino is of Italian American Catholic background. She graduated from Rosemont College in suburban Philadelphia. She has studied photography, off and on, since 1987 at the International Center of Photography in New York City. She was married to director John Byrum for a time, but they divorced in 1993. She is still very close to Byrum's children. She splits her time between Westport, Connecticut and New York City.