The Gunners today announced they have completed a move for the Germany international, 29.
Arsenal will pay around £20m for the Bayer Leverkusen goalkeeper, who will leave the Bundesliga after a seven-season spell.
And Leno has taken to social media to reveal his delight at joining the Gunners this summer, claiming he cannot wait to play under Unai Emery.
He tweeted: “Happy and proud to play [for] this great club @Arsenal in the future!
“I’ll do my best and I’m looking forward to the start of the new season as a Gunner.”
On Leno heading to the Emirates, Gunners boss Emery said: “We are very pleased that Bernd Leno will be joining us. Bernd is a goalkeeper of high quality and experience.
“He has been a top performer and regular number one goalkeeper with Leverkusen in the Bundesliga for the past seven years.
“We are all excited that Bernd has chosen Arsenal Football Club and look forward to start working with him in pre-season.”
Leno will become Arsenal’s second simmer signing, with the goalkeeper following Stephan Lichtsteiner to north London.
The Switzerland international completed his move to Arsenal earlier this month after joining on a free transfer from Juventus.