Leonardo Ulloa struck twice and Wes Morgan was also on target as the Foxes maintained their survival charge against a freefalling and disjointed Magpies side, who finished with nine men after Mike Williamson and Daryl Janmaat saw red.
John Carver’s men have now lost their last eight Premier League encounters in a row to remain in peril, still five points from safety, but with now only three games left to play this season.
Nigel Pearson’s side shrugged off a midweek defeat to Chelsea – as well as their manager’s now-infamous ‘ostrich’ rant at a journalist – to record a fourth win in five but Sunderland’s victory over Southampton means they remain just a point above the Wearsiders.
The Foxes were on the front foot from the off, immediately earning a corner from which Ulloa rose highest at the near post, powering Marc Albrighton’s inch-perfect left-wing delivery past a helpless Tim Krul with just 37 seconds on the clock.
And it did not take Leicester long to move further ahead, Albrighton again the provider with another dangerous delivery from the left which Morgan, just onside, stretched to get a touch past Krul (17).
The Magpies were toothless in attack in the opening period, the closest they came to testing Leicester goalkeeper Kasper Schmeichel being Emmanuel Riviere’s clever turn and shot from the left-hand corner of the box that flew inches past the Dane’s near post.
But whatever words Carver had for his bedraggled players at the break – and they must have been strong ones – were forgotten three minutes into the second half when Riviere clumsily pushed Marcin Wasilewski in the box following another dangerous looking Albrighton corner, referee Mike Dean having little option but to point to the spot.
Ulloa kept his cool to thump the resultant penalty high past Krul, and when the experienced Williamson proceeded to pick up two bookings in the space of a little over five minutes, Newcastle heads began to drop.
The visitors were fortunate, though, that Pearson opted to rest some of his key men in the closing stages otherwise they could have suffered an even heavier defeat, but their goal difference is now the second worst in the top flight.
Schmeichel was called upon late on to save from Siem de Jong but Newcastle went down with a whimper and were spared further blushes when Jamie Vardy headed wide in injury time.
But there was more misery before the whistle when Janmaat received his marching orders in second-half stoppage time after picking up a needless second booking, the Dutchman – like Williamson – now suspended for next week’s visit of West Brom.
Leicester City: Schmeichel (7), Wasilewski, (7) Huth (7), Morgan (8), Albrighton (8), James (7), Cambiasso (8), Schlupp (7), Mahrez (8), Vardy (9), Ulloa (8)
Subs: Kramaric (6), Hammond (6), de Laet (6)
Newcastle United: Krul (6), Janmaat (6), Williamson (5), Coloccini (6), Dummett (6), Colback (6), Taylor (6), Gutierrez (6), Sissoko (6) Perez (6), Riviere (5)
Subs: de Jong (5), Armstrong (6), Anita (6)
Man of the match: Jamie Vardy