Laurent Blanc's side now have 86 points to overtake Lyon's all-time record of 84 in 2006, in a tie which was overshadowed by PSG's France midfielder Yohan Cabaye suffering a right ankle injury. European places will now be allocated on the final day of the season next Saturday with UEFA Champions League and UEFA Europa League berths still up for grabs.
PSG's goals came through Brazilians Marquinhos (41) and Lucas (66) and Blaise Matuidi (83) with the titleholders bidding to close out their season on a further high at home against Montpellier next weekend. Cabaye picked up the injury late in the first half after a tackle for which Lille's France midfielder Marvin Martin was given his marching orders. The 28-year-old was stretchered off and taken to hospital immediately for a scan, which Blanc later said had not revealed anything serious.
"The ankle is very swollen, but obviously it was more fear than harm," Blanc said. "I didn't see it but yes I was scared. Obviously he must have been thinking of the World Cup."
Minutes later, Brazilian defender Marquinhos broke the deadlock with a header, with Zlatan Ibrahimovic, playing for the first time in a month, missing a chance to give the visitors a two-goal advantage just before the break. Lucas got the second after 65 minutes as he picked up a cross from Argentinian team-mate Javier Pastore, with the Brazilian also setting up the third as Matuidi gave the Lille defence the slip behind Ibrahimovic.
Midfielder Jonathan Delaplace got one back for the hosts in extra time, but it was too little too late as third-placed Lille are just two points ahead of Saint-Etienne, 3-1 winners at Nantes, thanks to a Mevlut Erding double.
Lyon were the big losers of the weekend as they could miss out on an 18th straight UEFA Champions League spot after losing 1-0 at home to Lorient. Lyon were reduced to ten men after just 14 minutes when Mouhamadou Dabo was red-carded, with Cheick Doukoure giving the Brittany side the only goal after 53 minutes. Lyon are fifth, just one point ahead of Marseille who shared the spoils 1-1 at Bordeaux, and could grab the final Europa League berth.
Nothing is decided yet at the bottom of the table, either, although Coupe de France winners Guingamp secured their top flight place next season with a 2-0 win at home against Toulouse.
The final Ligue 1 ticket will be decided in a winner-takes-all tie between Sochaux and Evian on Saturday after both won their ties. Sochaux won 2-1 at Rennes and Evian beat Nice 2-0.