An incident-packed game looked certain to end in a 1-1 draw after Martin Skrtel netted at both ends and sub Jermain Defoe also missed a penalty.
Several other clear-cut chances went begging for both sides before Lennon became the hero to move Spurs to within a point of fourth-placed Manchester City and back to six of the summit.
It was the second time in eight days, and the fifth time this season, Tottenham had come from behind to win a Premier League game.
Sunday's match was the first meeting between the sides since Tottenham usurped Liverpool as a member of the top four and one of England's Champions League flagbearers, a mantle they have assumed with aplomb.
They suffered a blow early on when they lost Rafael van der Vaart to injury in the 12th minute, the midfielder having been passed fit to play after an ankle injury.
Replacement Defoe curled a left-foot volley at Jose Reina before the lively Maxi Rodriguez forced a fine fingertip stop from Heurelho Gomes, who then improvised a save to turn Dirk Kuyt's angled volley behind.
Raul Meireles was cautioned midway through the half for felling Gareth Bale in full flight and referee Martin Atkinson had his yellow card out again for Paul Konchesky on the half-hour after a brilliant 40-yard run by the Tottenham winger.
A minute later, Defoe should have put Spurs ahead when Reina spilt Luka Modric's cross to leave him with an open goal but Jamie Carragher threw himself in front of the ball to block.
It was frantic stuff and David Ngog then powered a header wide from Kuyt's cross before Spurs suffered another blow when Younes Kaboul hurt himself after being hit by a Fernando Torres shot.
Sebastien Bassong came on for the final nine minutes of the half, which saw Gomes almost fumble Meireles' speculative shot into his own net and Carragher carded for tripping Modric in full flight.
Liverpool then snatched the lead when Spurs made a complete hash of trying to clear Meireles' flighted free-kick and Skrtel pounced to prod the ball past Gomes.
Maxi and Torres could have doubled the deficit in stoppage-time but the former fell over his own feet with only the goalkeeper to beat and the latter was thwarted by a brilliant last-ditch Bassong tackle.
Incredibly, Lucas Leiva sent Torres clean through again a minute after the restart and hesitated long enough to allow Bassong to challenge.
But Spurs were unlucky not to level in the 52nd minute when Lennon's cross eventually dropped to Bale and his vicious shot somehow found the head of Meireles on the line.
Atkinson was not interested when Peter Crouch went down in the box but did penalise Carragher for a challenge on Defoe which led to a 61st-minute Tottenham penalty.
In a repeat of the spot-kick they were awarded at Arsenal the previous weekend, Bale blasted a free-kick which Ngog inexplicably handled.
Skrtel was booked for disputing the award but it did not matter as Defoe dragged the penalty wide, Spurs' fourth miss from the spot this season.
However, an inspirational run from Modric did see Spurs equalise four minutes later, the midfielder jinking his way into the box.
Skrtel tried to cut out his cross but could only turn the ball past Reina.
Kuyt was adamant he should have had a penalty following a strong challenge from Benoit Assou-Ekotto but Atkinson was unmoved.
The visitors were forced to replace Ngog with Fabio Aurelio for the final 15 minutes.
Neither side were settling for the draw and Bale saw another effort blocked when his volley crashed into a crowd of Liverpool players.
The impressive Meireles also sent a beautifully-struck left-foot shot inches wide from 25 yards before the Reds lost Carragher for the final four minutes to a shoulder injury, Sotirios Kyrgiakos replacing him.
Glen Johnson was booked after leaving Bale in a heap, with light snow beginning to fall in north London.
Defoe then netted what he thought was a brilliant last-minute winner but he was offside lashing the ball home.
But, two minutes into stoppage-time, Lennon sealed another incredible Spurs fightback when he raced onto Crouch's flick and fired past Reina.
Defoe was immediately withdrawn for Sandro and Lennon almost made it 3-1 with another barnstorming run.