Hostin was born on October 20, 1968 in New York City to a Puerto Rican mother, Rosa Beza, and an African American father, William Cummings. Hostin was raised in The Bronx, New York City, attended the all-girls Dominican Academy, and is bilingual in English and Spanish. She received her B.A. degree in English and Rhetoric from Binghamton University and her J.D. degree from Notre Dame Law School.