Wilfried Zaha and James McArthur ripped the Foxes apart as they fired Palace to the brink of Premier League survival.
The pair set each other to score in a sensational first half for the Eagles – before Ruben Lofus-Cheek added a third after the break.
But while this victory pushed Palace further away from the top-flight’s trap-door, it may have nudged Claude Puel closer to the exit at Leicester.
The King Power boss has come under increasing pressure in recent weeks.
And his side’s woeful display here would have done little for his chances of keeping his job on an afternoon when they finished with ten-men following Marc Albrighton’s 58th minute sending off.
Leicester keeper Ben Hamer almost gifted Palace a ninth minute lead when he made a complete hash of fisting away a Yohan Cabaye corner.
But fortunately for the Foxes, Kelechi Iheanacho was on hand to clear James Tomkins’ shot off the line and spare stopper’s blushes.
It was then Eagles defender Joel Ward’s to be a goal-line hero as he blocked Jamie Vardy’s shot after it had beaten keeper Wayne Hennessey
Zaha broke the deadlock in the 17th minute when he fired home from James McArthur’s cheeky backheel following a good work by Ruben Loftus-Cheek and Yohan Cabaye.
It was the Ivory Coast star’s eighth Prem goal of the season for the Eagles – and he came close to grabbing another 12 minutes later when his toe-poke from inside the box was tipped around the post by Hamer.
But there was simply no stopping as his beautifully threaded pass across the box found McArthur, who swivelled and shot past Hamer to put the hosts 2-0 up seven minutes before the break.
Slow-starters Leicester have now conceded first in seven of their last nine matches.
Boss Claude Puel reacted by taking off Iheanacho and Hamza Choudhury at half-time and replacing them with Fousseni Diabate and Adrien Silva, but in truth the damage had been done.
The Foxes suffered another blow when Wilfried Ndidi limped off injured in the 50th minute.
And the visitors’ misery was compounded eight minutes later when Marc Albrighton was sent off hauling down Zaha as the Palace man was about to break clean through on goal.
Albrighton was clearly angered by the decision – even though it appeared correct – and the tirade of abuse TV pictures showed him aiming at ref Mike Dean could result in him receiving more than just the statutory ban.
Palace continued to push forward and went close to scoring again when McArthur dinked a shot into the side-netting after neat pass from Patrick van Aanholt.
Leicester’s travelling fans started chanting the name of former title-winning boss Claudio Ranieri as Loftus-Cheek rounded Hamer to score Palace’s third in the 81st minute.
Van Aanholt then steered a shot into an unguarded net to make it 4-0 after Hamer had raced off his line to block an effort from sub Jeffrey Schlupp.
Benteke put the cherry on top adding a late fifth… and rubbing salt into Leicester’s already gaping wounds.