The ACB side said in a statement that the player had told them about the deal.
Spanish media reported that the 27-year-old, rated as one of the top guards in Europe, will pay Barcelona 3.5 million euros ($4.80 million) to buy himself out of his contract.
Navarro's rights in the NBA were owned by the Washington Wizards.
He will join fellow Spaniards Gasol, Jorge Garbajosa, Jose Manuel Calderon and Sergio Rodriguez in the NBA.
All five were part of the Spain team that won the world championship in Japan last year, and are preparing for next month's Eurobasket 2007 to be held in Spain