Cech, the most successful keeper in Chelsea's history having won four Premier League titles and one Champions League, said he never envisaged leaving Stamford Bridge but had no choice after becoming second-choice to Belgian Thibaut Courtois last season.
“I thought this would never happen ... it is time for me to say goodbye to Chelsea,” the 33-year-old said in a personal message to the fans.
“The club I have lived every single minute for since joining in July 2004, the club in which I thought I'd hang my gloves and boots one day and finish my career, but life doesn't always turn out the way you think it will.
“Last summer things changed and I understood I was no longer the first choice...the limited playing time gave me the chance to refresh and rest mentally as well as make me realise just how much I enjoy playing football at the highest level,” said Cech.
“That's why I spoke to Mr Abramovich about me staying in the Premier League and I'd like to thank him from the bottom of my heart for his support in this matter. It means so much to me because without him Chelsea would not be where it is now.”
Cech, who will play one of his first games for Arsenal against his former club in the Community Shield at Wembley on Aug. 2, described his 11 years at Stamford Bridge as “an incredible journey”.
“I couldn't be more proud,” he said. “As a team we made history together. I would personally like to thank everybody involved with Chelsea for their support, all the players, staff, managers and coaching staff.
“But most important of all a huge thank you goes to all the Chelsea fans. I did everything for you and you gave me your love back. I'll never forget it, it will stay with me forever.”
Some of Arsenal's players have already welcomed their new team mate to the club.
“Wow what a signing! One of the best @PremierLeague keepers ever! Welcome @PetrCech,” Wales midfielder Aaron Ramsey said on his Twitter account.
“From blue to red - welcome @petrcech to the @Arsenal family,” added Germany playmaker Mesut Ozil. – Reuters
Original source: Cech thanks Abramovich for move