Blanc wins first trophy with PSG
Blanc took charge over the summer after Carlo Ancelotti left the Parc des Princes for Real Madrid, although his opening encounter in the PSG hotseat looked to be a forgettable one when former club Bordeaux took a 38th-minute lead through Henri Saivet.
Les Girondins were on course to spoil the party as they remained ahead with the game entering its final 10 minutes, but substitute Hervin Ongenda levelled and, with penalties looming, Brazil defender Alex became the unlikely match-winner with virtually the last kick of the game.
The league champions were on the front foot early on with the players looking to impress their new manager.
Lucas Moura released Ezequiel Lavezzi and his rasping long-range effort was palmed away by Bordeaux goalkeeper Cedric Carrasso, who could only watch on as Zlatan Ibrahimovic's lob from 25 yards only just went over the bar.
The Coupe de France champions were not content to sit on the back foot, however, and Ludovic Obraniak attempted to catch out PSG custodian Salvatore Sirigu, but the Poland midfielder's thumping strike was punched clear.
Bordeaux, for whom Blanc managed for three years from 2007, would not be denied, however, and they broke the deadlock when Saivet headed home at the near post following Nicolas Maurice-Belay's ball in from the left.
Spurred into action after the interval, Ibrahimovic picked out Lavezzi in a decent position but the Argentinian could only fire straight at Carrasso, while at the other end Maurice-Belay missed the target by inches as Bordeaux attempted to kill the game off on the counter-attack.
There was no urgency in PSG's play, though, and their lack of spark in the final third may give Blanc some food for thought, despite a frantic final few minutes.
They drew level in the 81st minute when Ongenda played a one-two with Ibrahimovic to go through on goal, where the 18-year-old made no mistake with his finish.
It seemed certain the match would be heading straight to penalties, but former Chelsea centre-back Alex popped up in the fifth minute of injury time, rising highest to head powerfully into the net from Moura's free-kick, to ensure Blanc had a memorable start to life as PSG coach.