The Poland international, who is in his third full season with the north London club, joined Arsenal's academy in 2006 from his hometown club of Legia Warsaw.
Arsenal manager Arsene Wenger told the club's official website: "We're very pleased Wojciech has signed a new long-term contract. I have always believed he is an extremely talented player, with excellent reflexes and good mental strength.
"He continues to grow and improve all the time too, so he has the potential to be even better. He can be an important part of Arsenal Football Club for many years to come."
Szczesny made his debut for the Gunners in a League Cup win over West Brom in 2009 and has featured 121 times for Arsenal.
The 23-year-old said: "I am very pleased to have signed a new contract. Arsenal is like my family and I'm so happy to be committing my long-term future here.
"I've been at this club for over seven years now and I'd just like to take the opportunity to thank everyone for their support towards me during my time here.
"Many people have given me amazing support since I arrived as a boy, people like (Arsenal goalkeeper coach) Tony Roberts, who helped my development as a player from a young age.
"I'm so proud to be an Arsenal player and am looking forward to helping our club towards success in the years to come."
Source: PA
Source: PA