In an overwhelmingly one-sided Classique, Unai Emery's side raced into the lead through early goals from Marquinhos and Edinson Cavani in front of a record crowd of more than 65,000 at Stade Velodrome.
Second-half goals from Lucas Moura, substitute Julian Draxler and Blaise Matuidi ensured the scoreline reflected the gulf between the two sides, despite Rod Fanni scoring a consolation for the hosts.
Marseille went into the game in a confident mood, having strung together three consecutive home victories, but Rudi Garcia's side were outclassed in all departments.
PSG became only the second team – after Monaco - to win at Marseille this season, and the emphatic manner of the victory will have delighted Emery, who was given no reason to give up hope of pushing free-scoring Monaco all the way.
It has been more than five years since Marseille last beat PSG, and Garcia could not point to the absence of injured top scorer Bafetimbi Gomis as a factor in the defeat; his team-mates were simply outplayed.
The stadium was silenced in just the sixth minute. Thiago Silva headed Marco Verratti's free-kick back across the face of goal and the onrushing Marquinhos thundered his header into the unguarded goal.
PSG continued to expose Marseille's defensive frailties and Layvin Kurzawa's header drew a fingertip save from Yohann Pele, but Dimitri Payet offered a reminder of the home side's attacking threat with a shot that flashed past Kevin Trapp's goal.
The visitors were irresistible going forward, though, and had a beautifully crafted second when Javier Pastore played an instinctive first-time throughball that Cavani latched onto before applying a delicate finish over Pele.
Lucas was denied a third by Pele's fast reactions after a defensive mix-up between Patrice Evra and Rolando, while Thiago Silva slammed the ball home after his header rebounded off the post but Cavani was ruled offside and the goal was disallowed.
Rather than offering a response after the restart, Marseille were slow out of the blocks and PSG rolled in a simple goal to make it three within five minutes of the restart.
Pastore, making his first start for PSG in five months, played a skilfull rabona-style cross to Lucas, and the Brazil international side-footed calmly past Pele into the corner.
Lucas almost added his second when he rose unmarked to head a corner towards goal but Pele was equal to it.
There was nothing the goalkeeper could do, though, to stop Draxler from making it four when he met Thomas Meunier's cross with a close-range finish.
Fanni's shot on the turn briefly reduced the deficit after Trapp's punch failed to clear a Marseille corner with 20 minutes remaining.
But the fightback lasted just two minutes before Marco Verratti danced through the penalty area before teeing up Matuidi to lash his finish high into the net and wrap up the victory.