The Hammers went into the game having drawn their three previous games, but looked to be set for a defeat after Jamie Vardy put Leicester in front in the first half.
The game then turned when Vardy was sent off for a second yellow card after diving inside the box, and West Ham were handed a lifeline when Andy Carroll converted a penalty, with Winston Reid being brought down by Wes Morgan.
Slaven Bilic's men then made it two goals in quick succession when Aaron Cresswell volleyed home from Michail Antonio's cross, and appeared to be putting a dent in Leicester's title hopes.
However, there was another twist in the tale as Carroll was controversially adjudged to have brought down Jeffrey Schlupp inside the penalty area, and Leonardo Ulloa scored the spot kick to hand Leicester a draw.
The game will be dominated by talk of refereeing decisions after some contentious calls at the King Power Stadium, all of which handed West Ham another point in their push for European qualification.
After the final whistle, Hammers co-chairman David Gold took to Twitter to give his view on the result, suggesting that Cresswell's stunning volley should have been the winning goal, but for a soft decision to hand Leicester a penalty.
Great goal from Aaron Cresswell deserves 2 be the winner, then a soft penalty against Andy Carroll for hugging Schlupp the Leicester sup. dg— David Gold (@davidgold) April 17, 2016
What did you think of West Ham's performance against Leicester?