According to the Mail, Cech could face his former club as early as August 2 for the Community Shield at Wembley.
Arsenal manager Arsène Wenger said: “Petr Cech is a player that I have admired for a long time and I am very pleased that he has decided to join us. He has proven over many seasons that he is one of the outstanding keepers in the world and he will add great strength to our squad.”
The 33-year-old, who signed for the Blues in 2004, made nearly 500 appearances for the West London club, but was frozen out last year after the arrival of Belgian stopper Thibaut Courtois.
Arsenal players were quick to take to social media to praise their new colleague...
— Mesut Özil (@MesutOzil1088) June 29, 2015
Cech, who is a four-time Premier League winner, four-time FA Cup winner, three-line League Cup winner and a Champions League winner, will trouser around £100,000-a-week at the Emirates.