It did initially look as though the Foxes' five-match winning run in the Premier League was set to come to an end as Richarlison gave the Toffees a shock first-half lead. Brendan Rodgers' men eventually broke their tough resistance as Jamie Vardy converted at the back post mid-way through the second period.
Iheanacho then had his say in the 94th minute as he scored when one-on-one with Jordan Pickford and despite being flagged offside, VAR awarded the goal and the three points to the home side.
Story of the Match
Despite the pressure heaped on Everton boss Marco Silva before the match, the Toffees actually produced a positive performance and could well have taken the lead if Djibril Sidibe's strike had been a yard lower.
Leicester always remained a danger though and Ayoze Perez fired a warning shot as he showed quick feet in the penalty area but put his low effort just wide of Jordan Pickford's far post.
The hosts were unusually frustrated though and that was compounded as Richarlison gave the hosts a lead by finishing off a clinical counter-attack by dispatching Sidibe's cross past Kasper Schmeichel with a fantastic diving header.
VAR has its say early on
With Everton defending extremely well, Rodgers' troops thought they had a great opportunity to equalise as a penalty was awarded for a foul on Ben Chilwell but VAR chalked off the original decision. That gave the visitors even more encouragement as they almost got a second, first through Dominic Calvert-Lewin's blocked shot and Michael Keane's header from a corner.
Those missed chances came back to bite Silva's team as Leicester roared back into the clash. Iheanacho, brought on by Rodgers, charged down the right-flank and played a perfect cross for Vardy who slammed the ball into the net.
The momentum then appeared to shift as James Maddison spurned a chance from close-range, putting the ball straight into the midriff of Pickford. Moise Kean however had the best opportunity as he almost caught Schmeichel off of his line but curled his shot marginally wide.
Iheanacho causes drama at the King Power
Time continued to tick down and just as it looked as though both sides were going to walk away with a point, Iheanacho latched onto Ricardo Pereira's through-ball and beat Pickford with a low finish. The offside flag seemingly cut his celebrations short but VAR again had another side, adjudging him in line and seeing Leicester claim the win.
VAR does its job
For all of the criticism that VAR has got this season, and deservedly so, it was crucial in this match today. Firstly ruling out the penalty, which was the correct decision, it also allowed Iheanacho to net the winning goal. With points so important in the Premier League, a wrong decision could set the tone for a team's season. However, no one can argue against correct decisions and that is what VAR awarded at the King Power Stadium.
Here's an aspect that nobody thought would be possible at the start of the season - Leicester are performing better than in their title winning season. With the victory against Everton, the Foxes have now chalked up a club-record six Premier League wins in a row and it was certainly deserved looking at the balance of play.
The end for Silva?
To the Toffees credit, they did perform much better at the King Power Stadium, frustrating one of the best sides in the league. They were concentrated, disciplined and defensively sound. However, it could be too little too late. The loss now leaves Everton 17th in the league and only two points above the drop zone ahead of the Merseyside derby in midweek.