The 23-year-old Switzerland international signed for the north London side on Wednesday after weeks of speculation linking him with a move to the club.
There have been a number of squad number changes for Arsenal this summer, with Alexis Sanchez taking the number seven shirt vacated by Tomas Rosicky and Aaron Ramsey taking the number eight left by Mikel Arteta.
And the Gunners have now confirmed that new signing Xhaka will wear the number 16 shirt left behind by Ramsey in his first season at the club.
Xhaka will be in action for his national side at Euro 2016 before he joins up with his Arsenal team-mates later in the summer.
Arsenal finished second in the Premier League table last season as they failed to keep up with Leicester City in the race for the title.
The north London side have not won the title since their famous unbeaten triumph in the 2003-04 season.
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