Dembele opened the scoring with an individual effort on 13 minutes and then netted a penalty midway through the first half as PSG threatened to run riot against struggling opponents.
However a Saint-Etienne side sitting in the relegation play-off place stemmed the tide and managed to pull a goal back through a Zuriko Davitashvili free-kick on 64 minutes.
PSG, who won the French Champions Trophy last weekend against Monaco in Doha, nevertheless held on and have won 13 and lost none of their 17 domestic league outings this season.
“I would like to congratulate Saint-Etienne because I loved the way they played, with no fear, attacking and pressing high. They were very daring and brave,” said PSG coach Luis Enrique, whose team maintained their habit of being wasteful in front of goal.
“Since the start of the season we have created lots of chances but struggled to score goals, but I think tonight we played pretty well in general,” said the Spaniard.
His side are on course to claim an 11th title in 13 years, with this victory at the Parc des Princes coming in response to nearest challengers Marseille’s 2-1 win away at Rennes on Saturday.
Roberto De Zerbi’s Marseille side look like the only potential rivals for Paris in the second half of the season, with third-placed Monaco now 12 points adrift of the leaders after a 2-2 draw at Nantes on Friday.
Man City on horizon
PSG are building towards a crunch Champions League clash at home to Manchester City on January 22, and Luis Enrique rested numerous key players here.
Captain Marquinhos was not involved at all, while Willian Pacho, Warren Zaire-Emery, Joao Neves, Vitinha and Desire Doue all began on the bench.
Instead there was a first start this season in defence for Lucas Hernandez, who has recovered from a knee injury, and 18-year-old prospect Senny Mayulu came into the midfield.
Saint-Etienne were looking to build on a victory at home to Reims last weekend in their first outing under new Norwegian coach Eirik Horneland.
They looked lively in the opening minutes, with Georgian winger Davitashvili forcing an early save from Gianluigi Donnarumma, but PSG soon seized control.
Dembele opened the scoring before the quarter-hour mark, the France winger cutting in from the right flank and firing low into the near corner on his left foot from just inside the box.
The hosts then won a penalty when an Achraf Hakimi cross struck the arm of Leo Petrot inside the box, with the referee pointing to the spot after being called across to the VAR screen.
Dembele sent the goalkeeper the wrong way from the spot for his second goal of the night, and his 10th of the campaign in Ligue 1.
Bradley Barcola then thought he had made it three before half-time only for his strike to be disallowed following another VAR review for a foul on Benjamin Bouchouari.
Saint-Etienne have notably lost 8-0, 5-0 and 4-0 on their travels this season but they pulled one back here just after the hour mark when Davitashvili curled his free-kick around the wall and in from 25 metres.
That made the final scoreline respectable, although the only sides behind them in the standings are the bottom two, Le Havre and Montpellier.
“All in all, Paris were by far the best team, but we fought until the last kick, and that I am happy with,” said Horneland, who arrived from SK Brann in his homeland.
Le Havre lost 2-1 at home to Lens earlier, despite taking the lead through Andre Ayew, with debutant Goduine Koyalipou and Deiver Machado scoring for the away side.
Rock-bottom Montpellier had two men sent off as they went down 3-1 at home to Angers, for whom Esteban Lepaul scored twice.
A brace by Emanuel Emegha helped Strasbourg to a 2-1 win at Toulouse.
© 2025 AFP