Angel di Maria scored in the 28th minute after being set up by Kylian Mbappé. Javier Pastoré doubled the advantage four minutes into the second half.
With Lille seemingly happy to limit the damage, the game appeared to be heading towards a routine win for the hosts when Anwar El-Ghazi struck four minutes from time for the visitors.
But any hopes of a shock draw were killed off when Mbappé hit the third in stoppage time.
The win sent PSG 12 points clear of Lyon, Monaco and Marseille who all have 32 points. Monaco can move to within nine points of the pacesetters provided they beat Troyes on Saturday night at the Stade Louis II. Lyon and Marseille play on Sunday against Amiens and Saint-Etienne respectively.