The result confirmed PSG as champions of France once again, although Luis Enrique's side had to survive long spells of pressure before getting the job done against their closest challengers.
Lens started the stronger side and created several early opportunities. Wesley Said went close on multiple occasions, while Adrien Thomasson also threatened as the home side tried to unsettle the visitors from the opening whistle.
PSG goalkeeper Matvey Safonov proved crucial throughout the contest. The Russian produced a series of important saves to keep Lens out, including a sharp stop to deny Said from close range before the break.
Despite spending much of the first half under pressure, PSG struck with quality when Ousmane Dembele intercepted a loose pass and released Khvicha Kvaratskhelia, who finished clinically to give the champions the lead.
Lens continued to push after half-time and came close several times. Sima hit the post, while Florian Thauvin had an effort ruled out for offside as frustration grew for the hosts.
PSG eventually sealed the victory in stoppage time when substitute Ibrahim Mbaye fired a powerful strike beyond Robin Risser to spark celebrations among the travelling supporters.
After the match, PSG manager Luis Enrique praised his side's mentality and defensive discipline.
"Today, we spent more time defending than usual," he said.
"But if you want to win trophies, you have to dominate both offensively and defensively. The team showed the mentality it needs to win."
Luis Enrique admitted this title had been tougher to secure than previous triumphs.
"This is the sweetest and hardest title to win of the three years we've had here," he added. "Lens did a very good job this season and pushed us all the way."
PSG wrapped up the championship with one match remaining and now turn their attention towards an ambitious finish to the season. They face Paris FC in their final league fixture before meeting Arsenal in the UEFA Champions League final later this month.
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