The northerners, who have 58 points from 29 games, played superbly throughout and won with goals by Aurelien Chedjou, Eden Hazard and Moussa Sow as they edge towards their first league crown since 1954.
Caen reduced the arrears through Youssef El-Arabi six minutes from time.
Paris Saint-Germain's hopes of playing in the Champions League next season took a knock as the capital side could only manage a 0-0 home draw against Lorient.
At Villeneuve d'Ascq's Stadium Nord, where Lille play until their new stadium is built next year, the home side were once again in a class of their own.
Rudi Garcia's side went ahead on the half-hour when their Cameroon defender Chedjou headed home from a Cabaye corner and made it 2-0 through Hazard shortly after the hour.
Sow, the league's top scorer, netted his 20th goal of the season when he tapped in from a Gervinho cross 17 minutes from time to put the result beyond doubt.
"We are on the right track. If we continue like this, it will be all good," Belgian midfielder Hazard, arguably the best Ligue 1 player this season, told French TV channel Foot Plus.
"We just put the pressure on Marseille. If they don't win, we'll have increased our lead."
