Kevin Berigaud opened the scoring after some fine play from Ryad Boudebouz and Bryan Dabo and young substitute Ellyes Skhiri were also on target for the home side.
It was a third win in a row for the 2012 title-winners, who have claimed four victories and one draw in six matches since Frederic Hantz was appointed coach at the end of January.
That run has lifted Montpellier seven points clear of the relegation zone, with Lille a point beneath them.
Runaway leaders Paris Saint-Germain visit Lyon on Sunday looking to extend their 46-match unbeaten run in domestic competition stretching back to March last year.
Laurent Blanc's side make the trip without injured duo Marco Verratti and Angel Di Maria as well as defender Serge Aurier, banished to the reserves until the March international break.
Before that, Monaco in second go to a Nantes side who have not lost in 15 outings since a 1-0 reverse in the principality in November.
If Monaco slip up and PSG win, the capital club would have a chance of securing a fourth consecutive title next weekend.