The Brazilian also expressed determination to make Arsenal “shine again”.
He said, “I’m very excited to become an Arsenal player – I can’t wait to start training and playing with my team-mates.
“I decided [to join] because Arsenal is one of the biggest clubs in the world. They have a new project with Mikel Arteta.
“I think this club deserves to shine again and I want to be a part of this project – to be a part of the Arsenal family is amazing. I’m very happy to do that.
“I come to try to win trophies, because this club deserves to win again, and I think you have to do the best as possible to win every game. I always train hard and go on the pitch giving 100 per cent to help this team to win games and to win titles as well.”
The 32-year-old won two Premier League titles, an FA Cup, a League Cup and the Europa League during seven years with the Blues, but moves across London on a free transfer with Chelsea unwilling to offer the multi-year contract he desired.
Willian sat out the FA Cup final when Arsenal beat Chelsea 2-1 earlier this month due to injury, but said the impact made by Arteta in his first season in management encouraged him to join the Gunners.
Although Arsenal will not have to pay a transfer fee, the move for Willian, who is reportedly set to earn £200,000 ($261,000) a week, has been criticised just a week after the club announced they are planning to cut 55 jobs due to damaging economic impact of the coronavirus pandemic.
However, the 70-time capped Brazilian international was one of Chelsea’s standout performers after football’s return from the coronavirus shutdown to help Frank Lampard’s men secure a place in the Premier League’s top four.