The 36-year-old has worn No.33 since joining Arsenal in the summer of 2015 but had worn No.1 throughout his time at Chelsea and Rennes.
Wojciech Szczesny had been the occupant of the jersey, though he had spent the first two seasons out on loan at Roma before subsequently joining Juventus.
"I already wanted number one when I came but it belonged to Wojciech Szczesny at the time," Cech said.
"Last season when he left, it was at the last possible moment so I couldn't get it either.
"When they asked me if I would take it this year, of course I was happy to have the opportunity.”
Cech’s new number was part of a string of changes the Gunners made before unveiling their new kit on Tuesday. Hector Bellerin took the No.2 shirt, Mohamed Elneny the No.4 whilst Granit Xhaka moved from No.29 to his preferred No.34.
