The Spain international and World Cup winning left-back has joined the Portuguese club on a two-year deal, ending his stint with the Yellow Submarine after four years
The World Cup winner has signed a two-year deal with Jorge Jesus' men, with a €20 million release clause inserted into the contract.
Last Monday, it was revealed that Benfica had opened negotiations with the Primera Division side over Capdevila.
The Eagles have been in the market for a left-back since Fabio Coentrao joined Real Madrid earlier this month.
Capdevila has won 59 caps for Spain, scoring four goals since making his debut in 2002. He played every minute of his nation's triumphant World Cup campaign last year.
The full-back enjoyed spells with Atletico Madrid, Espanyol and Deportivo La Coruna before joining Villarreal in 2007.