Thiago Silva's close-range effort set PSG on their way early on before Ibrahimovic tucked away a penalty following a foul on Marco Verratti.
Thiago Motta added a third just after half-time and then Ibrahimovic set up Edinson Cavani for the fourth.
The Swede made sure he stole the headlines, though, when he rounded off the scoring to maintain PSG's formidable home record that has seen them drop just two points out of the last 24 available.
Nantes, meanwhile, have now lost three of their last four league games.
PSG coach Laurent Blanc made seven changes to the side that defeated Bordeaux, including returns for Cavani and Ezequiel Lavezzi, both of whom joined Ibrahimovic in a fearsome three-man attack.
Nantes made two changes from the late Coupe de la Ligue win against Nice, but there was no place for Ismael Bangoura, who was on the bench.
PSG dominated the opening exchanges and went ahead inside 10 minutes when Cavani's flicked header from a corner was saved by Remy Riou and Silva was on hand to tap home the rebound from six yards.
Nantes, meanwhile, only had Chaker Alhadhur's blocked shot to show for their early efforts.
Their task was made harder after 35 minutes when a poor pass fell to Verratti in the area and, in his desperation to regain possession, Issa Cissokho could only bundle the Italian over for a penalty.
Ibrahimovic stepped up to score, although Nantes almost responded soon after when Lucas Deaux's surging run ended with a shot, but his strike could only find the side netting.
It was almost three in first-half injury time when Verratti's back-post cross found the onrushing Lavezzi, whose volley drifted just wide.
PSG continued to dominate, and they added a third soon after half-time when Gregory van der Wiel's deep cross was headed across goal by Blaise Matuidi and Motta was left with the simple task of volleying in from close range.
It was four after 58 minutes when Verratti's challenge set Ibrahimovic free and he unselfishly squared for strike-partner Cavani, who swept home with ease.
Ibrahimovic passed up a great chance to make it five after 62 minutes when he shot straight at Riou, but he made up for that uncharacteristic miss a few moments later by lashing a loose ball in from 12 yards, albeit via a deflection for his 28th goal of the season.
