The Sweden striker tapped in from close range midway through the second half after Argentina midfielder Javier Pastore had given PSG the lead late in the first half. Ibrahimovic also scored both of PSG's goals in a 2-1 win away to Lille on Sept. 2.
PSG, which drew its first three games, moved provisionally into third place with nine points ahead of this weekend's matches.
Also Friday, defending champion Montpellier lost 3-1 at Reims - its third defeat of the season.
Pastore struck in the 38th minute when he ran onto a lofted ball over the defense and lobbed the ball over goalkeeper Ali Ahamada as he rushed off his line.
Despite gritty defending from Toulouse, PSG gave itself some breathing space when France winger Jeremy Menez set up Ibrahimovic to score from close range in the 69th.
PSG spent around ?150 million on new players to prepare its bid for domestic and European success, and Ibrahimovic has taken little time to settle since joining from AC Milan.
The win will boost PSG's confidence ahead of Tuesday's home match against Dynamo Kiev in the Champions League.
Meanwhile, ahead of Tuesday's match against Arsenal, Montpellier coach Rene Girard gambled on leaving France center half Mapou Yanga-Mbiwa, wingers Remy Cabella and Anthony Mounier, and striker Souleymane Camara on the bench.
The move backfired as Brazilian midfielder Diego Rigonato gave newly-promoted Reims the lead in the 38th minute. Cabella scored two minutes after coming off the bench to equalize in the 55th with virtually his first touch of the game.
Montpellier fell behind again midway through the second half when center back Christophe Glombard scored, and substitute Gaetan Courtet came on to make the points safe in the 86th.
John Utaka had a good chance to put Montpellier ahead midway through the first half but goalkeeper Kossi Agassa saved with his legs. Utaka then went off with what looked like a groin injury, and was replaced by Camara.
Left back Henri Bedimo and midfielder Younes Belhanda then went close as Montpellier dominated, but Rigonato ran onto Nicolas Fauvergue's defense-splitting pass and coolly slotted the ball under goalie Geoffrey Jourdren's body as he came off his line.
Cabella leveled when he gathered the ball in midfield, sprinted forward, swapped passes with Belhanda and volleyed the ball past Agassa, but Glombard's goal was even better as he burst through the midfield with his raw pace and clipped the ball over Jourdren.
Glombard then set up Courtet to polish off an impressive second half.
''If we can keep playing like this, then I think we can definitely stay up,'' Fauvergue said.