The Gunners reportedly agreed a fee of €22 million (£19.3 million) for the 26-year-old, according to David Ornstein at BBC Sport.
Freelance football writer Lars Pollmann offered context on the transfer fee:
The goalkeeper is seen as the "long-term successor to Petr Cech," per Fabrizio Romano and Ed Aarons at The Guardian.
Cech turned 36 in May and has one year left on his deal. The veteran came under scrutiny for his displays last season, as shown by WhoScored.com:
Manager Unai Emery told the club's official website:
"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 was part of Germany's provisional squad for the 2018 FIFA World Cup but was one of the four players omitted from Joachim Low's final 23-man party along with Leroy Sane, Nils Petersen and Jonathan Tah.
Germany possess quality when it comes to goalkeepers with Bayern Munich's Manuel Neuer, Barcelona's Marc-Andre ter Stegen and Paris Saint-Germain's Kevin Trapp ahead of Leno in the pecking order.
Leno joined Stuttgart in 2014 and went on to become the club's first-choice goalkeeper. However, he is still capable of making errors, according to football journalist Chris Williams:
Hush Kerai at Sky Sports News explained why he will still be welcomed at Arsenal:
The goalkeeper does have an excellent record when it comes to penalties, as shown by Opta:
Leno becomes Arsenal's second signing under Emery. The club have already confirmed they have brought in Stephan Lichtsteiner from Juventus on a free transfer.
Arsenal are also expected to land Sampdoria midfielder Lucas Torreira and are hopeful of doing a deal during the World Cup, per Bruce Archer at the Daily Express.
Football writer Ben Fairthorne offered an update on Arsenal's summer transfer business:
Bringing in a new goalkeeper looked a priority for Arsenal this summer, and they have moved quickly to sign an experienced goalkeeper who will be expected to take over from Cech next season.