The visitors appeared to be heading for their first defeat of the season when Thiago Motta was adjudged to have fouled Mathieu Valbuena inside the area and was shown a harsh red card after 31 minutes.
Andre Ayew slotted home the penalty to leave PSG with a mountain to climb but they rose to the challenge superbly, Gabriel Heinze nodding in the equaliser on the stroke of half-time before Zlatan Ibrahimovic converted the winning penalty midway through the second period.
"The team always believed it could hit back," Blanc told L'Equipe.
"It's a huge satisfaction for the players.
"Once we scored the second goal we showed great solidarity and courage.
"We showed even in adversity that we could get it done and the 10 men stood up.
"There was great energy in defending and attacking, a significant physical impact from 10 against 11.
"In that aspect, we were better than Marseille."
The win moved PSG back to the top of the Ligue 1 table alongside Monaco.
Blanc refused to dwell on the performance of referee Clement Turpin, who angered the PSG players throughout an inconsistent display.
"I never discuss refereeing decisions, it is useless," he added.
"Once he has made his decision, it is irrevocable."
Motta was more outspoken, believing the referee had made a mistake in brandishing a red card for a fairly innocuous foul.
"Maybe the penalty was justified, but the red card is over the top," said the Italy international.
"The referee could not stand the pressure. It was not his day."
Marseille coach Elie Baup was also unhappy with the referee but conceded his players had again been found wanting against a top team following on from Champions League defeats to Arsenal and Borussia Dortmund.
He said: "The result, added to those against Arsenal and Dortmund, show that against teams which have big resources we have to make a big effort to move forward."
Baup felt the PSG penalty came as a result of the official looking to make amends.
"We felt that the referee was waiting to whistle any situation, we should have been less naive."