The Swede netted the second from the penalty spot in the 36th minute after Thiago Silva had put the hosts ahead following a 10th-minute corner that was parried into his path.
Ibrahimovic initiated the move that led to a third by Thiago Motta six minutes after the break, set up Edinson Cavani for the fourth and wrapped it up himself on 64 minutes to bring his season's league tally to 17 goals.
PSG top the table on 50 points from 21 games, five ahead of Monaco who won 2-0 at mid-table Toulouse thanks to a first-half goal Layvin Kurzawa and a splendid overhead kick by substitute Lucas Ocampos two minutes from time.
The French champions, who have scored 15 goals in their last four matches in all competitions, were never threatened by Nantes and captain Thiago Silva said they would get their chance on the European stage if they produce the same kind of performances.
"The boys have made a lot a great things tonight. We have to continue the same way and hopefully we'll play like that in the Champions League," he told French channel Canal Plus.
In Toulouse, it was not that easy for Monaco but goals from their youngsters helped them return to winning ways after a defeat and a draw in their last two league games.
"We have not played well after the winter break so I'm very happy with this victory. I hope that we're back on track," Monaco coach Claudio Ranieri told broadcaster beIN Sport.
Monaco still have issues to solve, including striker Radamel Falcao's two-month long goal drought. The Colombia international came close to scoring when he skipped past goalkeeper Ali Ahamada, only to see midfielder Abel Aguilar clear his effort off the goalline.
(Reporting by Gregory Blachier; Editing by Ed Osmond)
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