"I am very happy with the move, the decision and the club," Fabianski told the club's official website. "I'm very excited for the coming season and the coming years.
"It will be a big honour to represent Swansea City. Everyone interested in football knows that Swansea is a proper football club. The way they play football is nice to watch and they have always been an exciting team.
"Based on what the club has achieved in the three previous seasons in the Premier League, you can clearly see that year upon year the club is moving forward."
The 29-year-old played his last game for Arsenal in the FA Cup final at Wembley, where the Gunners secured a 3-2 victory over Hull City.