The Yorkshire strugglers lost their first seven Premiership encounters but a spirited display earned them a belated and hard-fought success at the eighth attempt.
The start to the campaign has been a real shock for everyone at Headingley after last term’s Powergen Cup triumph and successful fight against the drop.
The Tykes have played like strangers for much of the current season, bereft of confidence with even their renowned doggedness eroded.
But they showed impressive fortitude and character to overturn Northampton’s 17-6 advantage with two quickfire tries to establish a 23-17 interval lead.
It was an advantage which they did not surrender en route to a potentially priceless win.
Leeds were given an early boost when Gordon Ross converted a penalty after just two minutes, but Northampton came back strongly.
Skipper Bruce Reihana missed an eight-minute penalty but mercurial fly-half Carlos Spencer, who was sin-binned shortly before the interval, edged the visitors ahead four minutes later with a splendid try.
The New Zealand legend weaved his way through an undermanned Leeds rearguard to register a touchdown converted by Reihana to edge Northampton 7-3 ahead.
Another penalty from Ross after 17 minutes reduced the arrears to a point, but Saints soon exploited Leeds’ lack of cohesion to storm 17-6 ahead.
Reihana notched a 20th-minute penalty to make it 10-6 before wing Andy Vilk grabbed a scintillating effort after hacking Jon Clarke’s kick down the left flank and outstripping the Leeds defence.
Reihana again added the extras before the Tykes came roaring back to lead at the break.
Full-back Roland de Marigny started the ball rolling after 25 minutes with a close-range try from David Doherty’s neat grubber kick.
Ross again converted before Leeds wing Andre Snyman produced a devastating solo effort to edge his side ahead shortly before the half-hour mark.
Snyman collected the impressive Justin Marshall’s offload just inside the Leeds half and embarked on a penetrating run down the right flank, kicking and collecting his own punt to cross the line in the corner.
Another excellent conversion from Ross put Leeds 20-17 ahead before Spencer took centre stage again – only this time for all the wrong reasons.
An apparent stamping offence from the Northampton fly-half saw him sin-binned and with Leeds dominant, Ross added another penalty to send the hosts in at the break with a slender 23-17 advantage.
Reihana missed a penalty six minutes after the restart but Northampton soon began to pile the pressure on the hosts.
The Tykes, however, defended like demons and although Reihana grabbed a 65th-minute penalty to reduce the gap to three points, Leeds clinched the game with 12 minutes remaining when substitute Tom Palmer crashed over the line.
Ross failed to convert and Leeds were forced to endure a nervy ending when Seamus Mallon touched down in the left-hand corner.
Reihana failed to convert and then missed a long-range penalty as Leeds clung on for a precious victory.