Les Dogues become French champions for the fifth time in their history -- their last title came in 2011, when Eden Hazard was part of the squad. The club also won the league in 1933, 1946 and 1954.
PSG have failed to win the title for the first time since 2017, when Kylian Mbappe led Monaco to Ligue 1 glory. The Parisians have won seven of the past nine campaigns (2013, 2014, 2015, 2016, 2018, 2019 and 2020) but came up short this year.
Despite finishing fourth last season and second during the previous campaign, Christophe Galtier's side were not among the favourites for the title this time around. However, they had been top of the table for 18 of the 37 weeks of the season compared with nine weeks for PSG and three weeks for Lyon.
"It's a great performance. It's incredible," said Galtier, who is expected to leave the side he took over when they were set to battle relegation in 2017.
"It was a long, tough day, we were under a lot of pressure and beating PSG on the last day is outstanding," said Galtier. "The credit goes to the players. This team scored points against their title rivals. I can't forget that they beat PSG away after losing against Nimes at home.
"I love this squad. I love these players."
Lille have been consistent throughout the season and remain unbeaten in the matches against closest rivals PSG, Lyon and Monaco. They also boast the best away record in the league with 43 points from 18 games and have conceded only 22 goals -- a better defensive record than Manchester City, Bayern Munich and Inter Milan during their title-winning campaigns this season.
Despite some setbacks within the club through the season with a change of owner and chairman and the departure of sporting director Luis Campos, Galtier and his squad still managed to stay focused in one of the most exciting title races in Europe this season.
As well as great collective strength and the perfect blend of youth and experience, this Lille team has also relied on individual brilliance.
Mike Maignan has had a wonderful season in goal, while the centre-back pairing of Jose Fonte (37 years old) and Sven Botman (21) has been the best in the country. In midfield, captain Benjamin Andre (30) has led by example, guiding huge talents such as Boubakary Soumare (22) and former Bayern player Renato Sanches (23).
Up front, Burak Yilmaz was in sensational form during the final stretch of the campaign, scoring six goals in the past five matches.
The Turkey international had never played outside of his country, but at 35, he has been one of the standout performers and in contention to win the Ligue 1 player of the season award.
It compounds a disappointing campaign for PSG, who brought in Mauricio Pochettino to replace Thomas Tuchel in January after they endured a tough start to the season.
Earlier this month, the club were dumped out of the Champions League semifinals after a 4-1 aggregate defeat at the hands of City.