Andy Goode scored all Worcester's points as they ended a run of three Aviva Premiership Rugby defeats and extended Northampton's winless sequence to four games in the process in a scrappy contest at Sixways.
Fly-half Goode was on target with four from six penalty attempts as the Warriors edged their way to a deserved victory after claiming a 6-3 half-time lead, with Stephen Myler kicking the visitors' points.
Worcester boss Richard Hill had spoken of his side's need to match Northampton in the close exchanges, and his pack did him proud as they put major pressure on Saints strong set-piece and carrying game, while in full-back Errie Claassens they had the game's stand-out back.
While Saints are without several key players on World Cup duty this was an ineffective display, and boss Jim Mallinder will be concerned at the ill-discipline which allowed Goode to boot Worcester to the win, and saw prop Brian Mujati sin-binned in the second half.
Northampton put themselves under pressure from the off when wing Paul Diggin and full-back Greig Tonks failed to agree on who was going to claim a towering up and under from Claassens.
Saints' poor start continued as they conceded a soft penalty. Goode was off target from out on the right but made amends in the ninth minute from the opposite side.
Myler levelled matters following Northampton's first spell in the Worcester half but the hosts were playing with the greater fluency.
Flanker Jake Abbott made a foray into Saints territory before a lovely break from Claassens saw Miles Benjamin forced out as he closed in on the try line.
Claassens then produced another wonderful run after hitting the line at pace, but he was unable to hold on as he was brought to ground.
Worcester gained some reward for their greater attacking threat when Goode knocked over a monster penalty from just inside his own half to re-establish the lead on the half-hour, after Mujati was penalised for slipping his bind at a scrum.
Saints hit back with their best attack of the half as strong running from Jon Clarke freed Diggin, but the wing was expertly pulled down by Claassens and the chance was lost.
The second half started with another Goode penalty, although the former England fly-half also missed a presentable chance to add another three points as Northampton infringed again.
The steady stream of penalties continued with referee David Rose warning captain Phil Dowson, but it went unheeded as Mujati was sin-binned seconds later after illegally halting a close-range Worcester attack.
Despite their numerical disadvantage Saints went closest to grabbing the first try as wing Scott Armstong slipped through the home defence, but Worcester's determined rearguard action kept them out.
Goode missed a snap drop-goal attempt just past the hour-mark but his fourth successful penalty was enough to seal the win, with Saints replacement Ryan Lamb missing a penalty and drop goal effort late on as Northampton failed to pick up a losing bonus point.