After a goalless first half, Brazilian defender Maxwell broke the deadlock with a fine individual goal before Ibrahimovic doubled the lead.
The Sweden striker's second, his 34th league goal this season, was a volley and Edinson Cavani got the fourth.
PSG move to 89 points, 30 clear at the top.
PSG still have three league matches left - Ajaccio (away), Bordeaux (away) and Nantes (home).
Laurent Blanc's side last week added the Coupe de la Ligue to their Ligue 1 crown.
They will secure a domestic treble if they defeat Marseille in the Coupe de France final on 21 May.
Champions Paris St-Germain equalled their own Ligue 1 points record after two goals by Zlatan Ibrahimovic helped earn victory over Rennes.