The 25-year-old forward emerged from the substitute's bench to win the game for the Ligue 1 leaders, who were far from convincing ahead of their big night against Barcelona midweek
Kevin Gameiro came off the bench to score the only goal of the game with nine minutes to go for the hosts, who had their chances in the first-half, but saw their momentum slowly disappear thanks to an increasingly stubborn defensive performance from Rene Girard's men.
PSG provisionally extended their lead at the top of the table to eight points, though they were left with more questions than answers for their midweek Champions League clash with Barcelona after a display when they were far from their best.
Carlo Ancelotti named David Beckham on the substitute’s bench, as Alex and Gregory van der Wiel started in defence, while Jeremy Menez replaced Lucas on the flanks.
And the hosts could have been ahead in the first minute of the game had Clement Chantome been slightly more accurate with a shot from the edge of the box that whistled past the far post, following a terrific feed from Javier Pastore.
Though Montpellier stood their ground during the early exchanges, the better chances would fall PSG’s way, and with 20 minutes gone, Zlatan Ibrahimovic fired narrowly over the bar after he was picked out with precision by Marco Verratti.
Gaetan Charbonnier sliced the visitors' best opening of the half wide from 18 yards, but the home side continued to look more dangerous, with Ibrahimovic drilling off target again, before Geoffrey Jourdren denied Thiago Silva’s header superbly.
The Montpellier keeper also thwarted a similar opportunity from Alex, but should have been made to work a lot harder by Ibrahimovic minutes before the break, the Swede scuffing straight into his arms after taking aim from an unmarked position inside the box.
Montpellier would have two decent chances to take the lead shortly after the restart, as Remy Cabella’s finish from close range failed to do Souleymane Camara’s excellent run justice, before Charbonnier’s effort missed the bar by inches.
But as the minutes ticked away in the second half, so did the incisiveness of PSG’s attacking play as Montpellier proved themselves an increasingly tough nut to crack at the back.
Ancelotti threw on Beckham and Gameiro for Chamtome and Verratti with just under 20 minutes remaining, and the changes seemed to do the trick as momentum shifted back in his side’s favour.And with 81 minutes on the clock, the substitutes would play a part in winning the game for PSG. Beckham's pass started the attack, where Menez played in Ibrahimovic, who in turn slipped in Gameiro for a simple finish to seal the points.