A source close to the family has said De Niro and Hightower are now living apart.
Robert De Niro and his wife Grace Hightower are ending their marriage after over 20 years. The couple were married in 1997, after dating for 10 years. They have two children together, Elliot (20), and Helen Grace (6).
The couple first split a year after the birth of their son Elliot, in 1999. However, they decided to not finalise the divorce and renewed their vows again in 2004. Speaking on the situation at the time, De Niro said he wanted to "make sure this one sticks."
The 'Raging Bull' actor also has four other children. He and his first wife Diahnne Abbott have son Raphael, and he adopted Abbott's daughter Drena; he has twin sons, Aaron and Julian Henry, from a long relationship with former model Toukie Smith.
De Niro and Hightower were last seen publicly together on the red carpet in New York, at the 72nd Annual Tony Awards in June.
De Niro recently made a surprise appearance on 'Saturday Night Live'.