Fresh from their emphatic 5-0 hammering of Clermont, their biggest-ever victory in a Ligue 1 opener, PSG came into this clash at Le Parc des Princes with plenty to be optimistic about - especially with talisman Kylian Mbappe returning to the starting line-up after recovering from a hip injury.
However, while the hosts dominated the ball from the off, they found chances hard to come by early on. The best chance fell to Neymar, who failed to test goalkeeper Jonas Omlin after getting on the end of an exquisite Lionel Messi pass.
Jordan Ferri had a lucky escape after the VAR alerted referee Willy Delajod to the defender’s handball in his own area. Mbappe uncharacteristically had his penalty saved by a strong Omlin right hand before the keeper was called upon again soon after, this time to stop a Messi free-kick.
PSG got the breakthrough five minutes before the break, Falaye Sacko cruelly turning the ball into his own net trying to clear an Mbappe cross.
Sacko’s nightmare end to the half was compounded when he gave away another penalty, once more for handball. This time, Neymar stepped up and made no mistake as he slotted home his side’s second of the night.
The hosts wrapped up all three points shortly after the restart, sloppy Montpellier defending allowing Neymar to head the ball past the onrushing Omlin for his third strike in two games.
Wahbi Khazri made the most of a lapse in PSG concentration to pounce on a rebound and give Montpellier a glimmer of hope with 30 minutes remaining, but the hosts responded strongly to conceding their first goal of the season as Mbappe restored his side's three-goal lead.
Two minutes from time, new boy Renato Sanches got on the end of a cross to score on his debut.
Although Enzo Tchato fired home a consolation at the death, it was a night to forget for Montpellier, but there was little they could do against the Parisians in this form - ominously, Christophe Galtier's team already look a cut above the rest of the division.