After a goalless first half, the visitors went ahead three minutes after the restart thanks to Javier Pastore's header.
Lille got themselves back into the match from the penalty spot in the 70th minute when Mamadou Sakho was shown a red card for his foul on Nolan Roux. Eden Hazard stepped up to sweep the ball home and level the scores.
The killer blow came with 10 minutes to play as Roux nodded in from close range from Hazard's spectacular cross.
PSG are now five points behind leaders Montpellier with four games to play.