Ibrahimovic headed home 17 minutes from time to put the French champions on 57 points 21 games and give them a massive 23-point lead over second-placed Angers who lost 2-1 at third-placed Nice on Friday.
Laurent Blanc's team, however, did not have it all their way at Toulouse's stadium against a side who lie second-bottom of the standings on 20 points.
They also lost midfielder Javier Pastore and defender Marquinhos through injury in an industrious performance.
"It was a tough game but we were expecting it against a team fighting to stay in the top flight. However, we knew that if we stayed true to our principles we would score," PSG defender Serge Aurier told Canal Plus.
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Toulouse had the best chances in the first half and Wissam Ben Yedder's header was superbly saved by Kevin Trapp. The striker also hit the bar shortly before halftime.
PSG stepped up a gear after the break and in the 73rd minute, Cavani deflected Lucas's corner kick into the path of Ibrahimovic, who headed the ball past Alban Lafont to net his 16th league goal of the season.
Argentine playmaker Pastore limped off the pitch in the 19th minute with a possible calf injury, being replaced with Cavani and Brazilian Marquinhos picked up a groin injury just after the hour.
St Etienne and Olympique Lyonnais face each other in France's hottest derby at Geoffroy Guichard on Sunday.
(Reporting by Julien Pretot; Editing by Ed Osmond)
