The 25-year-old former Cannes full-back made 187 league appearances for the Gunners after arriving in 2003 for £250,000, scoring once against Stoke City in November 2008.
GEAR:Man City shirts available from just £18 throughKitbag. Free delivery on orders over £50
Clichy, who has won 10 caps for France after previously representing his country and under-15, 17, 18, 19 and 21 levels, has put pen to paper on a four-year contract at Eastlands, becoming manager Roberto Mancini's first signing of the summer.
“I’m really happy to be joining such a great club. I hope I can add to the quality we already have here because we have a fantastic squad who I believe will continue to get better," he told the club's official website.
“I can’t wait to get started and I think anything is possible with this team. When I first came to England, it was Kolo Toure and Patrick Vieira who took me under their wing and really looked after me.
“Kolo would pick me up and drop me at home and his wife used to cook meals for me. Patrick was always there to offer me advice so it’s wonderful to be back and at the same club they are at.”
Arsenal manager Arsene Wenger told the Gunners' official website: “We would like to thank Gael for eight years of terrific service to Arsenal, during which time he gave absolutely everything for the club.
"He has grown and developed so much since joining us in 2003, and has been a crucial part of the team over recent seasons. Gael leaves with our respect and best wishes. We wish him the very best for his future career.”
Clichy added his thanks for the support given to him by Arsenal fans throughout his eight-year stay in North London.
“I have had eight fantastic years at Arsenal and made many friends. I have so many great memories from my time at Highbury and Emirates Stadium," he said.
"I would like to say thank you to everyone at Arsenal for all of their support and friendship. I also want to send a big thank you to all the Arsenal supporters, who have always been so good to me.”
