All four of the home side's goals came in the second period and the victory has moved the French champions onto 89 points - 30 ahead of nearest challengers Lyon.
Rennes, meanwhile, remain in seventh spot and now five points off the top five.
The 50th minute brought the first goal of the match and it came from Maxwell, who found the back of the net after Edinson Cavani had chested into the Brazilian's path.
Four minutes later, it was 2-0 as Ibrahimovic poked a low Angel di Maria cross into the back of the net, before the Swedish striker smashed home from inside the box after Javier Pastore had delivered from the right.
Laurent Blanc's side were not finished, however, and had their fourth in the first minute of stoppage time when Cavani collected a through-pass from Marco Verratti before finding the back of the net.