It didn't take long for PSG to take the lead, as main man Ibrahimovic delivered following a passing move, which saw Blaise Matuidi and Gregory Van der Wiel combine, before the striker was found at the back post.
© Getty Images
Benfica missed the chance to equalise after the opening 15 minutes when Guilherme Siqueira's effort flew just over the bar.
The home side doubled their lead after 25 minutes when 19-year-old Marquinhos scored his third goal since joining PSG in the summer, with a simple finish having had the ball squared to him.
Things got even worse for Benfica minutes later when Ibrahimovic added his second in the 31st minute after rising above his marker to head home from a corner and put PSG 3-0 ahead going into the break.
The away side tried to test PSG's resolve again, but Sirigu made another great save to deny Miralem Sulejmani.
PSG looked to complete the drubbing by adding a fourth, but Edinson Cavani couldn't convert the rebound after Lucas Moura's initial shot was saved, though the first half's three goals were enough to ensure Saint-Germain recorded their 25th consecutive European game without defeat at home.