The record 10-time winners stormed to victory against their weakened opponents, who are more focused on maintaining their push for success in Ligue 1 and the Champions League.
Four different PSG players registered on the night, netting either side of Safwan Mbae's own goal to set up a meeting for the Parisians with Angers in next month's final.
Blaise Matuidi and Angel di Maria were next to test De Sanctis - two of 12 on-target attempts in the one-sided semi-final - but Cavani did add a second goal with a fine backheeled attempt 31 minutes in.
Cavani was denied another goal before the break by Mbae on the line, while Matuidi's own backheeled shot came back off the upright.
An own goal from Mbae six minutes after the restart was followed moments later by a fourth of the night, this time added by Matuidi who was picked out by Di Maria a few yards out.
Lucas Moura attempted to join the party with his well-taken attempt, which De Sanctis did well to get to, but Areola was also being made to work at times as he kept out Irvin Cardona 15 minutes from time.
There was still time for Marquinhos to add the fifth in added time, however, rolling the ball over the line after a shot from the edge of the area deflected nicely into his path.