The 34-year-old has played a back-up role at the Parc des Princes since his arrival in 2011 as the Parisian giants have established themselves as a force once again.
First-team opportunities have been few and far between for Douchez due to the form of Salvatore Sirigu, but the former Rennes man has won Ligue 1 twice, the Coupe de la Ligue and the Trophees des Champions on two occasions during his time at the club.
Douchez has his sights set on more success after a signing a deal that will see him remain at the club until June 2016.
"I have spent three and a half extraordinary years with Paris Saint-Germain, crowned with numerous titles and unforgettable moments," he told the club's official website.
"I wanted to extend this incredible human and sporting adventure."
Douchez made his only league appearance in the 4-2 defeat to Bastia last month, but has played all six domestic cup matches – including Wednesday's 2-0 victory over Nantes in the Coupe de France.
