It was Messi’s 496th career league goal in Europe, breaking Cristiano Ronaldo‘s scoring record for Europe’s top five leagues.
Lens secured second place and automatic entry into next season’s Champions League by beating relegated Ajaccio 3-0 at home.
Defending champions PSG overtook former French powerhouses Saint-Etienne, who won their 10th title in 1981 but were relegated to the second division last season.
“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.”
PSG have won nine of its 11 titles since Qatari backers QSI took charge 12 years ago, with the first of those in 2013. PSG’s other titles were in 1986 and 1994.
“This is of course an historic moment for Paris Saint-Germain. This 11th French league title is the reward for all the hard work we have put in over the last 12 years,” said PSG president Nasser al-Khelaïfi, who has been in control since 2011.
“To make Ligue 1 history and overtake Saint-Etienne is a real source of pride.”
The title will be celebrated next Saturday at Parc des Princes when PSG hosts Clermont in what is set to be Messi’s last game for PSG.
Sources told ESPN earlier this month that Messi will leave PSG when his contract expires this summer. The 35-year-old has an offer from Saudi Arabia and he is aware of interest from former club Barcelona and Major League Soccer club Inter Miami, sources added.
Messi has felt the ire of PSG fans at times this season after his form dipped following his return from Argentina’s victory at the World Cup, and he was suspended by the club this month after an unauthorized trip to Saudi Arabia.
But in the end it was his goal that allowed the fans to celebrate — and gave Messi a 43rd career major trophy for club and country.
Information from Reuters was used in this report.