Britain's Daily Star claims the couple exchanged vows in a recent Buddhist ceremony, attended by a few family and friends, but Pitt's publicist Cindy Guagenti insists the story is "completely not true."
She states, "They've used a wedding picture from (movie) Mr And Mrs Smith and run with this story on the front page. There's simply no truth to this whatsoever."
Though the couple have been romantically linked ever since they played man and wife in spy comedy Mr And Mrs Smith, neither has commented on the speculation.
The Daily Star reported the actor is wearing a gold band on his wedding finger since the alleged ceremony and the pair plan to go public as a couple once a legal ceremony has taken place.