Laurent Blanc's side are still unbeaten in Ligue 1 this season, but their inconsistent performances have led fans to question the tactics of the former France boss.
Blanc was without his talisman Ibrahimovic, who scored 26 league goals last season and already has five this term, for the second consecutive game and his team looked devoid of ideas going forward as Toulouse pressed high in the opening stages.
The hosts took a deserved early lead when Wissam Ben Yedder fired home, but PSG replied before the break thanks to Jean-Christophe Bahebeck's maiden goal for the club.
Blanc's men lived dangerously throughout the first half and Toulouse would have been two up had Aleksander Pesic not squandered a close-range chance.
However, Marco Verratti eventually found enough space to play in Bahebeck, who finished confidently into the bottom corner to bring the champions level, but that was as good as it got for PSG.
Toulouse started superbly and were ahead after just eight minutes when top scorer Ben Yedder latched onto Serge Aurier's sloppy backpass.
The diminutive forward then coolly rounded Salvatore Sirigu before squeezing the ball past David Luiz at the near post for his fifth goal in eight games.
Ibrahimovic bagged a hat-trick in the corresponding fixture last season and his influence was clearly missed in the opening stages, while Ben Yedder's excellent movement caused havoc for the visitors at the back.
Alain Casanova's side squandered a gilt-edge chance to extend their lead when Sirigu palmed Ben Yedder's shot into the path of Pesic, who failed to convert into an empty net.
And the Serbian was made to pay when PSG levelled in the 33rd minute through Bahebeck's strike, the 21-year-old's first of the campaign.
Bahebeck, a product of the Parisian's academy, raced behind the Toulouse defence before slotting calmly beyond Zacharie Boucher.
A largely uneventful second period began in scrappy fashion, with neither side being able to sustain possession long enough to spark an attack.
Toulouse did manage to carve out the first chance of the half in the 70th minute, but Ben Yedder elected to pass when it seemed a shot would be a better option.
Blanc made three changes for the final 17 minutes, with Verratti, Yohan Cabaye and the out-of-sorts Edinson Cavani all making way, but their replacements fared no better.
The home team were awarded a free-kick on the edge of the box with late on, but Ben Yedder fired a curling effort wide.
PSG missed the chance to go level with Marseille at the top and face the daunting prospect of welcoming Barcelona in the UEFA Champions League on Tuesday.
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