Rivera was born at Beth Israel Medical Center in New York City, New York, the son of Lillian (née Friedman; October 16, 1924 – June 3, 2018) and Cruz "Allen" Rivera (October 1, 1915 – November 1987), a restaurant worker and cab driver respectively. Rivera is a Stateside Puerto Rican; his father was a Puerto Rican Catholic, and his mother was of Russian Jewish descent. He was raised "mostly Jewish" and had a Bar Mitzvah ceremony. He grew up in Brooklyn and West Babylon, New York, where he attended West Babylon High School. Rivera's family was sometimes subjected to prejudice and racism, and his mother took to spelling their surname as "Riviera" to avoid having bigotry directed at them (and only his sister Sharon did not have her surname misspelled).