The former couple married in 1980 and separated in 2006, but did not go public with their split until 2009 when Mel Gibson was photographed embracing a girlfriend.
The Gibsons have seven children together. Mel Gibson has a daughter from a subsequent relationship.
People.com said the Gibsons did not have a prenuptial agreement, so Robyn Gibson was awarded half of Mel Gibson's fortune, which the Los Angeles Business Journal estimated in 2006 to be $850 million.
Mel Gibson's career has been overshadowed in recent years by his battle with alcoholism and legal troubles.
He made headlines in 2006 for making anti-Semitic remarks during a drunken driving arrest, but later apologized for his actions. The Oscar-winner's public image was further tarnished when audio apparently of him making racist and abusive remarks toward his ex-girlfriend Oksana Grigorieva were leaked on the Internet.
Grigorieva accused him of assaulting her. The actor denied any wrongdoing, but pleaded no contest to a domestic violence charge and was placed on probation in March.