The result means PSG have an unassailable 12-point lead over second-placed Monaco, who have three games left.
The Ligue 1 triumph is PSG's third in a row and a record-extending 12th overall.
Mbappe has been involved in six of them, but comes off contract at the end of the season and is expected to be signed by Real Madrid.
PSG could have secured the title on Sunday (AEST) but were held 3-3 by Le Havre.
"Our fans are incredible. We were losing 1-0, 3-1, and they kept supporting us," coach Luis Enrique said after the draw.
"We managed to draw later on and effectively win the league thanks to the supporters, thanks to their positive attitude."
Un 1�⃣2�⃣ème titre acquis �������� ! ��💙— Paris Saint-Germain (@PSG_inside) 🗣� ��� �'��� �����#ParisiensEtChampions pic.twitter.com/IsrZYFHMhdApril 28, 2024
PSG are still on course for a historic treble as they'll play at Borussia Dortmund in the first leg of the Champions League semi-finals on Wednesday and face Lyon in the French Cup final on May 25.
In Enrique's first season at the club, PSG have produced one of the most dominant seasons with just one loss in 30 games so far.
The club have also reached the symbolic milestone of 50 trophies in their history, 32 of which have been won since the Qatar Sports Investments took over in 2011.
"Winning the league is fantastic, but to win Ligue 1 for the 12th time makes it even more special for everyone connected to Paris Saint-Germain," president Nasser Al-Khelaïfi said.
"I will also never forget the fans, who have been amazing whatever the result. We will treasure this moment together as a family."
Elsewhere, third-placed Brest made club history by qualifying for any European competition for the first time with a 5-4 win over Rennes.
Fourth-placed Lille kept pace with Brest in the race for Champion League spots by rallying to beat relegation-threatened Metz 2-1.
Fifth-placed Nice beat Strasbourg 3-1 and seventh-placed Marseille snapped a five-game winless run by edging Lens 2-1.
Toulouse secured safety by rallying past relegation-threatened Lorient 2-1 and bottom side Clermont kept alive their hopes of safety by stunning Reims 4-1.
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