The 27-year-old Italy international has won two Ligue 1 titles and the Coupe de la Ligue with PSG since he joined the club from Palermo in 2011.
"I want to continue this great human and sporting adventure with Paris Saint-Germain," the shotstopper told the club's official website. "I know we're only at the beginning of something special. We will still win many titles together!"
Sirigu has been capped 10 times by Italy at senior international level.