Laurent Blanc's PSG retained the French championship in midweek despite losing at home to Rennes and atoned for the muted festivities by producing a winning performance at Stade Pierre-Mauroy.
After Marvin Martin saw red for the hosts following his crunching challenge on Yohan Cabaye, Marquinhos opened the scoring shortly before half-time.
Lucas Moura and Blaise Matuidi put the champions out of sight with second-half goals but Jonathan Delaplace would pull a goal back for Lille at the death.
Yet when the dust had settled, Lille found their grip on third place had slipped as rivals St Etienne had closed to within two points of snatching their Champions League berth by beating Nantes 3-1.
Guingamp assured themselves of Ligue 1 football for another season as they beat Toulouse 2-0.
With Sochaux and Evian playing each other next week there is no way Guingamp can be caught by the two sides below them who remain in trouble, and they can now revel in staying up after only being promoted a year ago.
Any nerves they may have had were put to bed with five minutes gone as Claudio Beauvue scored and then Mustapha Yatabare put away a 14th-minute penalty.
Sochaux's great run of form continued with a 2-1 victory at Rennes but they remain in the relegation zone with one more match to go.
Herve Renard's men took the lead in the 34th minute through Jordan Ayew and, after Paul-Georges N'Tep equalised in the 73rd, fellow substitute Emmanuel Mayuka restored the advantage five minutes later.
Their final-day opponents Evian remain just on the right side of the danger line after a 2-0 win over Nice.
Kevin Berigaud and Nicolas Benezet scored the goals for the home side, who face Sochaux in a winner-takes-all battle next week.
Relegated Ajaccio sent their home fans away for the summer with at least something to cheer about after beating Reims 2-1 on their final appointment at the Stade Francois-Coty.
Elsewhere, Bastia moved into the top half with a 2-0 win at Montpellier, while St Etienne kept their hopes of Champions League football alive with a comfortable 3-1 win at Nantes.
Three men were sent off as Lyon lost 1-0 to Lorient and lost their grip on fifth place, although rivals Marseille themselves stuttered to draw 1-1 at Bordeaux, while Nabil Dirar's late strike saw Monaco scrape a 2-1 victory at relegated Valenciennes.