Belgian midfield prodigy Hazard, 20, beat keeper Nicolas Penneteau with a fierce angled shot two minutes into stoppage-time to take Lille clear of second-placed Stade Rennes who lost 2-0 to Olympique Marseille on Friday.
Rudi Garcia's pacesetting side have 52 points from 27 games, with Olympique Lyon and Marseille four points off the pace in third and fourth respectively.
"We had possession but failed to create a lot of chances," said Hazard, voted the best prospect in Ligue 1 in 2009 and 2010.
"There are still 11 games left and we take nothing for granted," he told the Foot Plus TV channel. "Let's try and grab as many points as we can as our rivals will finish strongly." Paris Saint-Germain were held to a 2-2 home draw by 10-man Montpellier.
PSG were 2-0 up after 14 minutes thanks to Guillaume Hoarau's header and an own goal by defender Mapou Yanga-Mbiwa.
At their Stadium Nord in Villeneuve d'Ascq, Lille took the lead after 39 minutes when Ligue 1's leading goalscorer, Moussa Sow, netted his 18th of the season with a 20-metre shot that went into the top corner after taking a deflection off Milan Bisevac's leg.
