Thomas Meunier and Thiago Silva scored either side of a Zargo Toure own goal, while Edinson Cavani and Lucas rounded off the scoring as third-placed PSG moved on to 39 points from 19 games, five behind leaders Nice, who were held to a goalless draw at Girondins de Bordeaux.
Nice finished with nine men after Mario Balotelli and Younes Belhanda were sent off in stoppage time.
Monaco are second on 42 points after goals by Radamel Falcao and Tiemoue Bakayoko earned them a 2-1 home victory against Caen.
At the Parc des Princes, PSG were rewarded for their early dominance when Meunier put them ahead in the 25th minute with a fine lob from just inside the box.
The home side doubled the lead a minute before the interval when Cavani's effort was deflected into his own net by Toure.
Silva put the result beyond doubt in the 51st, heading home from Lucas's corner, while Cavani rubbed salt into Lorient's wounds by converting a penalty shortly after the hour for his 18th league goal of the season. Lucas added a fifth with a lob 20 minutes from fulltime.
Monaco put last weekend's home defeat to Olympique Lyonnais behind them with victory over Caen.
They took the lead three minutes into the second half when Falcao converted a penalty after being brought down in the box and Bakayoko doubled the tally 14 minutes from fulltime with a 25-metre effort.
Herve Bazile pulled one back in stoppage time for Caen, who were reduced to 10 men when Damien Da Silva was dismissed in the 51st minute.
Lyon, who have a game in hand, are fourth on 34 points after goals by Alexandre Lacazette and Nabil Fekir gave them a 2-0 home win against Angers, while sixth-placed Olympique de Marseille (30) notched up their fourth straight win by beating Bastia 2-1 away.
Ligue 1 will resume on Jan. 13.
(Reporting by Julien Pretot; Editing by Toby Davis)
