Chelsea has announced the signing of the Argentine,who is expected to provide back-up to number one Thibaut Courtois next season.
“I am looking forward to meeting the guys and helping the club achieve more success in the coming season.”
Technical director Michael Emenalo added: “We are very happy to have Willy on board. He knows the Premier League and is tried and tested at the top of the game.
“We have three experienced goalkeepers and we look forward to welcoming him to the club when the squad returns to pre-season training.”