Laurent Blanc's side began Ligue 1 poorly as Remy Cabella's strike threatened defeat before a second-half equaliser, though a winner was not to be found
A first-half goal from Remy Cabella gave Jean Fernandez's men a shock lead and it required Maxwell to score midway through the second period to salvage a point for the hosts. Edinson Cavani's introduction from the bench could not provide a winner, despite the home side being reduced to 10 when Abdelhamid El Kaoutari saw red for a second booking.
PSG coach Laurent Blanc named record signing Edinson Cavani on the bench, with Zlatan Ibrahimovic partnered in attack by Ezequiel Lavezzi.
Siaka Tiene made his debut for Montpellier after joining from PSG in the close-season, with Cabella playing in behind Emanuel Herrera up front.
The visitors edged the early stages of the contest and came close to taking the lead when Lavezzi headed an in-swinging free kick from Lucas Moura straight at Montpellier goalkeeper Geoffrey Jourdren.
However, it was Jean Fernandez's men who surprisingly seized the initiative 10 minutes into the contest as Cabella dispossessed Ibrahimovic in midfield before reacting quickest to pounce on Herrera's deflected effort and fire past Salvatore Sirigu from a tight angle.
PSG crafted an almost instant response: Christophe Jallet hitting a left-footed effort over the bar from close range following good work from Ibrahimovic.
Montpellier's threat slowly faded as the half dragged on and they had Jourdren to thank for keeping them in front after 27 minutes as he produced a fine diving save to repel a long-range drive from Ibrahimovic.
However, Blanc's side were regularly frustrated by some last-ditch Montpellier defending and Cabella almost snatched a second goal six minutes before the break as he found space on the edge of the area, but he could only poke narrowly wide of the post.
Montpellier held on until the interval, but had to survive early scares in the second half, Ibrahimovic and Lucas both going close with free-kicks as Blanc's men emerged with renewed confidence.
Fernandez attempted to try and stem the tide of PSG attacks by bringing midfielder Jonas Martin on for winger Anthony Mounier.
However, the champions' pressure eventually told on the hour mark, Maxwell - who scored in a 1-1 draw in the same fixture last term - slamming home from close-range after Ibrahimovic diverted Marco Verratti's lofted pass into his path.
Cavani was introduced 71 minutes into the game, coming on in place of Lavezzi, and the tide swung firmly in PSG's favour moments after the Uruguayan's introduction, as Montpellier defender Abdelhamid El Kaoutari was sent off for a second bookable offence following a foul on Javier Pastore.
The extra man nearly told immediately, but Cavani was prevented from completing the comeback as his far-post header was blocked by Tiene.
Cabella was undeterred by his side's numerical deficiency, and he almost regained the lead for Montpellier in audacious fashion, lobbing just over the bar from long-range 10 minutes from time.
PSG pressed with increasing urgency, but they could not break down a determined home defence, Pastore firing wide late before substitute Adrien Rabiot's point-blank header was brilliantly saved by Jourdren in injury-time.