The result put PSG on 85 points, four ahead of RC Lens, who secured second place and a place in next season’s Champions League – a first for the Sang et Or in 21 years – with a 3-0 hammering of AC Ajaccio in a boiling hot Bollaert-Delelis stadium.
“Everything was not perfect, but this title belongs to the players. Being French champions is always something,” said coach Christophe Galtier.
“From a personal point of view I appreciate it a lot.”
Asked about his future at the club after one season in charge, Galtier said: “I’ve been reading a lot of things here and there but there is a difference between what’s being written and what’s happening.”
Olympique de Marseille will finish third after being left with 73 points following a 2-1 home defeat by Stade Brestois.
Lille are fourth on 66 points after a couple of Jonathan David penalties gave them a 2-1 home win against relegation-threatened Nantes.
Stade Rennais leapfrogged Monaco into fifth place with a 2-0 victory against the principality side, who are behind on goal difference with 65 points, leaving the fight for a spot in the Europa League to be decided in the final round of matches.
The fourth-placed team qualifies for the Europa League group stage, where they will join French Cup winners Toulouse.
In Strasbourg, PSG were their usual disappointing selves until Messi opened the scoring with a right footed effort into the top corner after collecting Mbappe’s pass in the area.
Strasbourg had their chances but failed to convert as they secured their place in the elite for next season.
Troyes, Ajaccio and Angers were already relegated and they will be joined into Ligue 2 either by AJ Auxerre or Nantes.
Nantes trail the Burgundy side by two points before hosting bottom side Angers while Auxerre will entertain Lens.
Lens won their ticket for Europe’s premium club competition as Lois Openda became the club’s top scorer in the top flight with 20 goals – level with Roger Boli who reached that tally in the 1993-94 season.
Openda scored the third goal with a penalty after Deiver Machado and Adrien Thomasson had put the hosts ahead in the first half.
“It puts me right up there with a club legend, I’m so happy,” said Belgium striker Openda.
“We did it all together, we were so strong at home this season,” said Lens defender Kevin Danso