The Sea Shepherd captain, who was detained in Germany on an international arrest warrant from Costa Rica officials last week (ends18May12), will host an SOS event at the festival - just two days after he walked free from jail in Frankfurt.
He still faces extradition to Costa Rica to stand trial on charges of putting the lives of fishermen at risk during a high seas protest over shark-finning a decade ago (02).
A spokesman for Watson tells WENN, ""The Cannes event will be an effort to free Paul Watson so he can continue to stop the destruction of habitat and the slaughter of wildlife in the world's oceans and conserve and protect ecosystems and species everywhere.""
Watson and Rodriguez, who has joined the conservationist and his Sea Shepherd organisation for various ocean campaigns, will also promote new documentary Confessions of an Eco-Terrorist at Cannes, which premiered at the festival a year ago (11) and documents the history of the Sea Shepherd Conservation Society leader, including the incident that landed him in hot water in Costa Rica.
Watson was released from jail on Monday (21May12) after spending eight days in custody. He is currently free on bail.
As the documentary maker and star campaigns for his freedom at Cannes, Sea Shepherd volunteers and supporters around the world will demonstrate outside German embassies and consulates to demand Watson's freedom.
He is scheduled to stage a press conference from the beach of the hotel Le Martinez in Cannes on Wednesday night (23May12).