De Niro and Hightower named their baby girl Helen Grace, who joins big brother Elliot, 13.
The actor’s rep confirmed the birth of the baby on Friday.
De Niro has four other children. He has two adult children from his first marriage to Diahnne Abbott and 16-year-old twin boys with his former girlfriend Toukie Smith, also born via a surrogate mother.
Robert’s wife Grace, 46, is a former flight attendant and they have been married since 1997.