This win was so comfortable that, toward the end of the first half, the home fans were already singing unpleasant songs about Marseille the bitter rivals meet in a domestic match on Sunday and Blanc was even able to experiment with his formation.
"What reassures me is that we hardly conceded a chance," Blanc said. "Benfica came here saying they wanted to control possession, but they will go home feeling unsatisfied."
PSG remains unbeaten this season and has not lost at home in European competitions since November 2006.
"We came up against a very good team, it's as simple as that," Benfica coach Jorge Jesus said. "They showed the weight of their investment. They reached the quarterfinals last season without losing a game and they will be even stronger this season. I think they can win the competition."
Blanc started with his favored 4-3-3 system, with Ibrahimovic captain in the absence of injured defender Thiago Silva flanked by Ezequiel Lavezzi and Edinson Cavani.
Blaise Matuidi found space near the penalty area and his pass behind the Benfica defense allowed right back Gregory van der Wiel to run on and square the ball perfectly to give Ibrahimovic his 32nd goal overall in the Champions League.
Artur saved Matuidi's low shot and Ibrahimovic forced a corner after some impressive trickery as PSG pushed for a second goal, which duly arrived in the 25th.
Thiago Motta's corner from the left was not properly cleared, and fell to Marco Verratti. He showed a delicate touch to flick a pass to Matuidi, who whipped the ball across from the byline and Marquinhos turned the ball in.
"Marco's a very good player and he has exceptional quality with the ball at his feet," Blanc said. "Verratti and Thiago Motta complement each other very well."
Benfica could not cope with Ibrahimovic, who rose imperiously at the back post to head home Motta's corner from the right just five minutes later.
"We paid the price for not starting the game focused enough against a strong team like PSG," Benfica midfielder Enzo Perez said.
Benfica missed a half-chance in the 18th when Cardozo got the better of Marquinhos and helped the ball along to left back Guilherme Siqueira, but his shot went way over.
The visitors finally had a scoring chance just after the restart, when center half Ezequiel Garay's swerving freekick was punched away by goalkeeper Salvatore Sirigu.
PSG sat back in the first 15 minutes of the second half, but Benfica did little with the extra space.
Blanc switched to a 4-4-2 formation with 20 minutes to go, giving Cavani the chance to play in his preferred center forward role.
Substitute Lucas made an immediate impression when he came on, breaking through the middle and hitting a low shot that Artur palmed away. The rebound fell to Ibrahimovic, but the ball was slightly high when it reached him, and a difficult hat-trick chance looped over.
Artur then made a fine save with his legs as Cavani tried to stab the ball in from close range in the 74th.
