Midfielder Tom Huddlestone was sent off when he received his second yellow card in the 72nd minute but Hull held on for a point and will feel they were the team who should have won the game.
Nikica Jelavic somehow missed a fantastic first-half opportunity and then sub Abel Hernandez squandered a chance to grab a late winner.
However, the visitors are now six points clear of the drop zone while the games are running out for bottom club Leicester, who are seven points from safety.
Desperate for three points from a winnable home fixture, Leicester produced plenty of first-half endeavour but struggled to create clear-cut chances, Michael Dawson and his fellow defenders proving resolute in the Hull back-line.
The visitors looked the classier outfit and carried the greater goal threat but Jelavic produced an incredible miss in the 20th minute.
Huddlestone picked out Ahmed Elmohamady with a lovely floated pass and the industrious Egyptian winger unselfishly cushioned the ball into Jelavic’s path, only for the forward to somehow miss his kick with the goal gaping.
Jelavic did shoot home five minutes later but the referee had already blown up, Dame N’Doye having barged into Mark Schwarzer as the veteran goalkeeper gathered a cross.
Schwarzer had kept his place despite the return to fitness of Kasper Schmeichel, who was on the bench, and the Aussie was fairly untroubled in the opening period, as was Hull keeper Allan McGregor.
Andrej Kamaric showed off a nice bit of skill before shooting wide from distance for the hosts but also made surprisingly little effort to dive in and make contact with an enticing Riyad Mahrez cross.
Leicester then began the second-half brightly and Esteban Cambiasso had a shot blocked after a Matty James cut-back before McGregor was finally called into action, forced to tip a mis-hit Jamie Vardy’s cross over the bar.
Hull defenders Dawson and Alex Bruce then both picked up seemingly harsh bookings and the way players from both sides surrounded referee Jon Moss will raise eyebrows in a week when Chelsea players were condemned for such behaviour.
The Hull players were again unhappy with Moss in the 72nd minute when Huddlestone, who had been booked in the first half, picked up a second yellow card for illegally halting an enterprising Vardy run.
Leicester’s raucous fans scented a chance for victory but the hosts were cruelly denied from the free-kick following the red card.
The set-piece was cleverly tapped to Jeffrey Schlupp and he unleashed a low shot from just inside the area which looked destined for the bottom corner, only to hit his team mate – sub Leonardo Ulloa – and bounce to safety.
That piece of misfortune summed up the day for the Foxes but they continued to press and Vardy volleyed over, before embarking on another surging run down the left and cutting the ball back to David Nugent, who shot just wide at the near post.
Hull would probably have settled for a draw at this point but suddenly had a chance to claim all three when N’Doye put Hernandez in on goal with a clever quick free-kick. However, the substitute did not get much power on his shot and Schwarzer pulled off a fine save low to his right.
Leicester kept pouring forward manfully at the other end but Mahrez put a long-range free-kick straight at McGregor and the hosts now need a remarkable run of results if they are to beat the drop.
Soccer Saturday verdict – Paul Merson
“If you look over the whole game, Leicester never really looked like scoring. It was not like they peppered the goal. They have been unlucky this season in certain games but not today.
“I thought the referee did well until the second half, when he booked Dawson – never a foul. He booked Bruce – never a foul. He then got sucked in by Vardy with Huddlestone. It was not a sending off for me, Vardy just ran across the lad and dived.
“Hull were the better team in possession. Leicester played with a lot of enthusiasm and you can’t knock their work rate but, when they get in the final third, there is no guile about them. That was a must-win game for them.”
Leicester: Schwarzer (7), De Laet (7), Morgan (7), Huth (6), Upson (6), Schlupp (6), Mahrez (6), Cambiasso (7), James (6), Vardy (8), Kramaric (6)
Leicester subs: Lawrence (6), Ulloa (5), Nugent (6)
Hull: McGregor (7), Dawson (8), Bruce (7), McShane (6), Elmohamady (7), Livermore (6), Huddlestone (5), Ramirez (6), Robertson (6), N’Doye (6), Jelavic (5)
Hull subs: Meyler (6), Hernandez (5), Quinn (6)
Man of the match: Jamie Vardy