The midfielder first went down extremely easily to win his side a penalty in the first half, which was emphatically scored by Youri Tielemans.
But then the 25-year-old pulled off one of the passes of the season to send Harvey Barnes in on goal, who squared it to forward Patson Daka to double their lead.
Maddison was involved once again for the third, as he received the ball inside the box, before simply laying it off to Tielemans to fire in his second of the game.
And he capped off an astonishing display with a goal five minutes from time, sending the ball past Martin Dubravka in the Newcastle goal.
The Magpies lacked any sort of quality in the final third throughout the game - something they will be hoping to rectify in the January transfer window after their Saudi takeover.
Jonny Evans went off with an injury inside the first five minutes of the contest, adding to Leicester's injury woes at the back.
It meant midfielder Wilfried Ndidi had to cover in central defence, with the likes of Wesley Fofana, Jannik Vestergaard, and Daniel Amartey all currently unavailable for selection.
Tricky winger Allan Saint-Maximin caused problems for the home side from the off, with right-back Timothy Castagne picking up an early booking after hauling down the Frenchman.
But it was Brendan Rodgers' skilful midfielder, Maddison, who helped put his side ahead, after he was brought down by Lascelles inside the penalty area just before half-time.
The former Norwich man jinked inside from the right, before he theatrically tumbled over the Magpies captain's leg inside the box.
Peter Bankes pointed to the spot, despite claims from the Newcastle players that Maddison had gone down too easily.
The referee disagreed, which just left Tielemans to emphatically fire into the top left corner to put the hosts ahead.
Newcastle lacked quality going forward, with the likes of Saint-Maximin, Joelinton and Callum Wilson failing to convert chances at the start of the second half.
And that came back to haunt them, as Leicester took a 2-0 lead just before the hour-mark.
Maddison flicked an unfathomable pass through to teammate Barnes, who beat the offside trap to bear down on goal.
The winger then unselfishly squared the ball to Daka, who put the ball into an empty net and gave the Foxes a two-goal lead.
Newcastle pushed to get back into the game, as Saint-Maximin and Shelvey both had effort from outside the box, but nothing to really test goalkeeper Kasper Schmeichel.
And it was nearly a defensive mix-up that led to the visitors pulling a goal back.
Castagne completely misjudged his pass-back to Schmeichel, who had to desperately chase back and clear it off the line.
Tielemans netted his second of the game with ten minutes to play, as the Leicester attack worked the ball nicely before Maddison put it on a plate for the Belgian to fire into the roof of the net.
But Rodgers' side weren't done there, as Maddison played a one-two with Daka, before firing into the far corner and continuing his fine goalscoring form.
The 25-year-old was replaced by youngster Kasey McAteer - who came on for his Premier League debut - to a standing ovation.
That was just Leicester's second clean sheet of the season, with the three points bumping them up to eighth.
Newcastle, on the other hand, remain second bottom of the league.