He said: "It is always a tricky business when you arrive at a new club. There are great expectations from the supporters and I hope that my way of working, of playing, will win the hearts and minds of the other players, the supporters and all those who work for Arsenal.
"This is my main goal at the club - I managed to win over the supporters at Fenerbahce and I hope the same will happen here. I arrive here with one aim: being a champion. I will wear Arsenal's shirt and give my utmost to it. I will do everything for the club.
"I am delighted to have signed for Arsenal. It was one of my dreams to play for a major European football club and I have accomplished this. I am very happy to be part of this team.
"All the Brazilians who came to this club spoke wonders about it and I am delighted to be part of the Arsenal family."