The length of the deal was not disclosed, only that it was a "long-term" commitment.
Fabianski told the club's official website: "I'm very happy to sign my new contract with Arsenal. It's a big motivation for me to keep working hard and shows that the club believes in me.
"I'll be doing everything I can to repay that belief by helping Arsenal to win trophies in the coming years."
Fabianski broke into the senior international side in 2006 and has since become a regular in the Poland squad.
He said: "I rate Lukasz highly and I am very pleased that he has committed his future to the club.
"I believe he is a top competitor, he's intelligent and reads the game very well and has all the ingredients to be successful in his position."