Mr Styron's daughter, Alexandra, said the author died of pneumonia at Martha's Vineyard Hospital, Massachusetts.
The author who had homes in Martha's Vineyard and Connecticut, had been in failing health for a long time.
Mr Styron’s obsessions with race, class and personal guilt led to such tormented narratives as Lie Down In Darkness and The Confessions of Nat Turner, which won the Pulitzer despite protests that the book was racist and inaccurate.
His other works included Sophie's Choice, the award-winning novel about a Holocaust survivor from Poland, and A Tidewater Morning, a collection of fiction pieces.
Mr Styron also published a book of essays and the best-selling memoir Darkness Visible, in which he recalled nearly taking his own life.
Mr Styron was a liberal long involved in public causes, from supporting a Connecticut teacher suspended for refusing to say the Pledge of Allegiance to the United State flag to advocating for human rights for Jews in the Soviet Union.
In the 1990s, Styron was among a group of authors and historians who successfully opposed plans for a Disney theme park near the Manassas civil war battlefield in northern Virginia.