Willian will wear the No 12 shirt after finally sealing his move to Arsenal.
The 32-year-old was a free agent after leaving Chelsea, having spent seven years at Stamford Bridge, and has penned a three-year deal with the Gunners.
Willian had rejected the offer of a two-year extension with the Blues, paving the way for him to join their London rivals.
Arsenal head coach Mikel Arteta admitted he was impressed by Willian’s desire to join.
“I believe he’s a player that can really make a difference for us,” said Arteta.
“We have been monitoring him for the past few months, we had a clear intention to strengthen in the attacking midfielder and the winger positions; he is a player that gives us a lot of versatility, he can play in three or four different positions.
“He has the experience of everything in the football world but to still have the ambition to come here and contribute to bring the club where it belongs. I have been really impressed with all the talks I have had with him and how much he wanted to come.”
