Almunia leaves Arsenal to join Zola at Watford
Almunia is one of seven new signings made by manager Gianfranco Zola and joins the London club on a one-year deal.
"Former Arsenal goalkeeper Manuel Almunia has signed for Watford," the Premier League club confirmed on its website.
"The 35-year-old was released by the club this summer but will be training next door to his former team-mates in London Colney after agreeing a one-year deal with the Championship side."
Almunia played 175 games for Arsenal including a substitute appearance in the 2006 Champions League final against Barcelona, but lost the jersey to Pole Wojciech Szczesny.
Watford were recently taken over by the Pozzo family who own Italian Serie A club Udinese and Spanish La Liga club Granada.
Other new arrivals include QPR defender Fitz Hall and several loan acquisitions from the fellow Pozzo family stable of clubs.
Almen Abdi, Matej Vydra and Steve Leo Beleck joined from Udinese on-loan as have Granada pair Daniel Pudil and Ikechi Anya.