After a sluggish start under new coach Unai Emery this was PSG's fourth successive victory and it moved them into second, level on points with leaders Monaco.
Nice, also on 29 points, are in third on goal difference but can go clear with the right result at Saint-Etienne on Sunday.
PSG's win, whilst not spectacular, will at least have put them in the right frame of mind ahead of next week's Champions League clash with Arsenal.
But PSG will have to sweat over whether Di Maria will figure in north London as after scoring early on he had to come off in the 25th minute with an apparent thigh problem.
The Argentine winger's place was taken by Hatem Ben Arfa.
Di Maria's injury could be worrying news for Emery, who is already without Alphonse Areola, Layvin Kurzawa and Adrien Rabiot.
But Emery said afterwards: "I hope he'll be okay for Wednesday," adding that Di Maria had asked to come off "I think as a precaution".
Nantes, despite their modest 16th place in the table, were posing plenty of problems to their well-heeled hosts.
They could easily have levelled with Guillaume Gillet's scissor kick in the 24th minute, his acrobatic attempt only denied by Kevin Trapp.
PSG had their German goalkeeper to thank for a quickfire double save to preserve their first-half lead just before the interval.
PSG's nerves were finally settled in the 90th minute when Javier Pastore was felled in the box with Real Madrid recruit Jese Rodriguez converting the resulting penalty.
Pastore, on as a late substitute for his first appearance after a calf problem since the end of September, ended the game hobbling off with a knee injury.
"I think, I hope it's only a minor injury but we'll see once the doctor's examine him," commented the PSG coach.
According to Emery, PSG had struggled to put the game to bed due to concentration, or lack of it.
"It's not easy to focus coming back after the international break and before the Champions League," said the Spaniard.
"The three points are important for the league and to prepare for the match on Wednesday."
On Friday, Falcao lashed home seconds after coming on in Monaco's 3-0 away win at bottom side Lorient.