PSG substitute Randal Kolo Muani scored the late winner, converting a rebound in the 83rd minute after goalkeeper Alban Lafont saved a header from Lucas Hernandez.
Bradley Barcola had given PSG the lead by rounding Marcus Coco to slot into the far corner just before halftime, but mid-table Nantes grew bolder in the second half and Egypt striker Mostafa Mohamed equalised with a header in the 55th minute.
"Bradley Barcola is the present and the future of this club, and we like young players joining us to know that we are going to give them confidence and minutes," PSG coach Luis Enrique said.
"(Barcola) was superb tonight. He was our best player in one-on-one situations. He scored an exceptional goal and it was a really good performance."
PSG lead the table by six points over second-placed Monaco, who won 2-1 at Rennes despite playing the last 15 minutes with 10 men following the dismissal of Vanderson for a second yellow card.
Vanderson had side-footed Monaco into the lead shortly after halftime and Youssouf Fofana doubled their advantage in the 85th minute.
Rennes pulled one back with a penalty from Benjamin Bourigeaud in the dying moments after Fofana brought down Desire Doue.
Rennes had European ambitions at the start of the season but are nervously placed in 12th, three points above the relegation playoff spot.
"There has clearly been a loss of confidence for weeks," Rennes coach Julien Stephan told Amazon Prime.
"We must refind some consistency and confidence, improve the quality of our play and be tougher in the game, much tougher."
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