Leeds were closing in on a much-needed three points in their quest for safety thanks to Luis Sinisterra's 20th-minute header after Leicester's Youri Tielemans had a goal ruled out.
The 36-year-old Vardy, who came on in the 70th minute, had other ideas though and fired past Leeds keeper Illan Meslier from James Maddison's pass to rescue his side.
It was his first league goal since October and the former England striker thought he had given Leicester the lead shortly afterwards but his effort was ruled out for offside.
A frantic finale saw Leicester keeper Daniel Iversen make an outstanding save to keep out Marc Roca's close-range header before Leeds striker Patrick Bamford scuffed a glorious opportunity wide.
The result did little to ease either side's relegation fears with Leicester remaining in 17th place with 29 points, one point ahead of third-from-bottom Everton who would move above them if they avoid defeat by Newcastle United on Thursday. Leeds have 30 points.
Second-from-bottom Nottingham Forest could also leapfrog Leicester if they win at home to Brighton & Hove Albion on Wednesday.
VARDY RAZOR SHARP
Vardy, whose goals powered Leicester to a fairytale title in 2016, has cut a frustrated figure this season and had not scored in any competition since a League Cup game in December.
But he looked razor sharp after interim manager Dean Smith sent him on and he drilled a low shot into the corner after a sweeping Leicester move ended with Maddison playing him in.
"It could be massive. We have five cup finals left. We'll enjoy the point tonight, then get back in and recover," Vardy said. "I can't say what I want to say on TV because I'll get done but it's been a weird season for me. Hopefully the goals keep coming."
Defeat would have been harsh on Leicester who were denied an early lead when Tielemans seized on a loose ball and sent an unstoppable shot into the top corner.
Sadly for the Belgian, a VAR check deemed Boubacary Soumare had been slightly offside in the build-up.
There was a nervous energy around Elland Road after three successive defeats but there was an explosion of relief when a superb move down the right saw Jack Harrison deliver a superb curling cross that Sinisterra headed down and into the net.
Javi Gracia's Leeds seemed content to try to hang on to their slender advantage in the second half and, with Maddison pulling the strings, Leicester took charge.
Meslier twice denied Kelechi Iheanacho, who went off injured, before Vardy's crucial contribution.
It was arguably a better point for Leicester who should have a smoother run-in than Leeds who still have to play Manchester City and Newcastle United in their last five games.
"We try to put the past behind us, learn from our mistakes and continue on in a positive way," Harrison said.
"We're looking for every point we can get in this moment in time. It's not what we wanted but we will take it."
