Shinji Okazaki's wonderfully-taken overhead kick was the highlight of a tentative first half, in which Newcastle gave the Leicester defence a few worries without really testing Kasper Schmeichel in the Foxes' goal.
A brief spell of Leicester pressure saw Jamie Vardy knock a deflected cross downwards, and his strike partner Okazaki produced a match-winning stunner, hitting an overhead kick low into Rob Elliot's net from just outside the six yard box.
Lack of end product from the visitors
A cagey opening half didn't have many clear-cut chances for either side, but Marc Albrighton came close to a second Leicester goal when he burst through and saw his placed shot go just wide of the Newcastle net. Arguably Newcastle's best effort of the opening 45 minutes came when Moussa Sissoko beat Danny Simpson to the ball at the far post, but his early header was woefully misdirected.
As Claudio Ranieri's men looked to press home their advantage in the early stages of the second half, Rafael Benitez introduced Andros Townsend for Vurnon Anita in a bid to add a much-need creative spark for the visitors. However, as in the first half, they seemed to have the upper hand without fashioning much to get the travelling Geordies out of their seats.
Newcastle's ever-growing confidence certainly kept the home fans nervous, as they restricted Leicester to a handful of broken-down counter-attacks in the early stages of the second half.
Sensing Leicester's anxiety, Newcastle tried to fashion an equaliser. Sissoko fired a volley goalbound, but Wes Morgan blocked, prompting half-hearted appeals for handball. On 85 minutes, Siem De Jong mis-hit a good opportunity from just inside the area and the ball trickled into the arms of a grateful Schmeichel. The late introduction of Seydou Doumbia didn't produced the desired effect, as Leicester clung on for a priceless 1-0 win.
It wasn't a vintage performance for either side, but at the full time whistle it was Leicester celebrating after a scrappy, anxious Monday night affair.
For Benitez and Newcastle, a point or three against this season's unlikely league leaders would have been a bonus and so they will be encouraged by this display. Rafa's men looked a lot harder to break down than the side Bournemouth walked through at St. James' Park. However, with eight games left to find the results to preserve their Premier League status, the Tyne-Wear derby this coming weekend has become ever more important.