They are the parents of two children, Elliott, 20, and Helen Grace, 6.
Hightower is a philanthropist who also has had minor acting roles in movies and on TV.
The pair have had marital issues before. De Niro filed for divorce in 1999, but the two reconciled and renewed their vows in 2004.
The actor was was previously married to Diahnne Abbott from 1976 to 1988 and they are the parents of two children, Drena, 47, and Raphael, 42.
In 1995 he welcomed twin sons, Aaron and Julian, with his girlfriend at the time, Touki Smith.