Former Nice coach Christophe Galtier decided against starting Mbappe, but it did not appear to matter when Lionel Messi opened the scoring from a free-kick he had won himself.
That was Messi’s first direct free-kick goal for PSG – and the 60th of his career – yet Gaetan Laborde equalised two minutes into the second half for Nice.
Although Mbappe’s introduction on the hour did not initially make much difference, the France forward’s quality told as he swept in an 83rd-minute winner at the Parc des Princes.
PSG failed to find the net in all three meetings with Nice last season, but that scoreless streak was ended by Messi with 28 minutes played of Saturday’s encounter.
The Argentina international was tripped by Dante 22 yards from goal and dusted himself down to send a sublime free-kick up and over the wall into the top-right corner.
But the visitors were level in the 47th minute when Laborde converted a cross that neither Nordi Mukiele, Marquinhos nor Gianluigi Donnarumma could deal with.
PSG toiled, despite the introduction of Mbappe, but the prolific forward had the final say when firing home after being picked out by a Mukiele cutback.
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Nice took four points off PSG in Ligue 1 last season and also eliminated the Parisians from the Coupe de France on penalties at the last-16 stage.
Now in the opposite dugout, Galtier almost had a taste of his own medicine as his new charges were pegged back by his old side and largely frustrated.
But Mbappe’s eighth goal in eight league outings this term ensured PSG finally got the better of Nice as they leapfrogged Marseille at the top of the table.
Messi’s free-kick masterclass
Messi kept up his fine start to his second season in the French capital by making it five goals in nine league appearances on top of his seven assists.
His strike left Kasper Schmeichel rooted to his spot, adding to the 50 direct free-kicks he scored for Barcelona and nine for Argentina.
Not so Nice defending
Mbappe only had one training session ahead of this match, but Galtier had no qualms bringing on the 23-year-old when requiring a goal with half an hour still to play.
That winner came via Mbappe’s only shot of the match, and it was entirely avoidable from Nice’s perspective as Marvin Bard gave the ball away in the build-up following a poor pass from Schmeichel.
Both sides switch focus to European action in midweek, with PSG travelling to Benfica in the Champions League and Nice at Slovacko in the Europa Conference League.