Heskey scored in the second half with a fine chip over Ian Walker after a run from midfield, his first since November and only his second in 35 games for club and country since August.
It was a solid performance by Liverpool, never exciting, but with top of the Premiership rivals winning all over the country - to add to Manchester United's success the previous night - this was one game the Anfield club could ill-afford to foul-up like they have done in previous home games against strugglers.
And if Heskey wore the proudest smile at the end, not far behind was Jamie Carragher, who never put a foot wrong at left-back after a traumatic few days.
His mood had no doubt been helped earlier in the day by being told the FA and police were not going to take any further action following the coin throwing shame of Highbury.
Liverpool took the risk of leaving Michael Owen on the bench as well as Danny Murphy and John Arne Riise, no doubt anticipating a regulation victory.
There was no Steven Gerrard either, with a neck problem, but the run-outs given to Gary McAllister, Vladimir Smicer and Patrik Berger failed to initially spark Liverpool out of the gloom that followed their FA Cup exit at Highbury.
With new signing Abel Xavier watching from the directors' box, Liverpool were predictable and lacking in drive early on.
Leicester, with seven men out either injured or suspended, knew they needed to improve on a recent run of four points from their last eight league games.
But their intention was clear to stifle play, with five in midfield, and it largely worked for the first half, at least.
Predictably lacking in confidence after their own cup exit, Leicester were penned back as Liverpool dominated possession but failed repeatedly to turn it into penalty box chances.
Dietmar Hamann saw a 30-yard free-kick flash over the crossbar in the first minute, and another long-ranger clear Ian Walker's goal on 16 minutes, but in between Liverpool created precious little.
Liverpool eventually began to up their pace and almost scored on 24 minutes when Jerzy Dudek's long throw released Vladimir Smicer down the right. His pass found Stephen Wright overlapping in the box, and the young full-back's shot beat Walker but was hacked off the line by Jacob Laursen.
Matthew Jones flashed a fierce shot wide and the Midlanders, having survived thus far, came to the conclusion that Liverpool were not at their best and started to come forward with more conviction.
And on 32 minutes Matthew Piper, whose pace had troubled Liverpool, collected the ball in the box and spun to his left before drilling over a low cross that was deflected to Matt Elliott, but the Scot's shot was charged down by Emile Heskey, the ball sailing over the bar from 10 yards.
Liverpool started the second period with more desire, and Heskey had a shooting chance stabbed off his toes by Davidson after a surge down the left.
And it was Heskey who broke the deadlock on 57 minutes, and his relief after such a barren run was obvious.
Hamann won the ball in midfield from Izzet and it set Heskey surging away from the halfway line to go clear of Elliott to cleverly chip Walker to put Liverpool ahead.
Three minutes after Heskey's goal, things got even worse for Leicester when the industrious Jones was carried off after being hurt following a challenge with McAllister, Lee Marshall coming on.
Heskey could have had a second soon after when he missed from eight yards as he tried to head Berger's free-kick wide of Walker.
Murphy and Riise got into the action as replacements for Berger and McAllister, and Leicester made a fleeting attempt to add some extra firepower with Trevor Benjamin's introduction, but it was too little too late for Dave Bassett's boys as they slipped ever nearer the First Division.