With their England centre Ben Te'o somewhat bizarrely rested and sitting in the stands, Worcester were poor as Northampton fly-half Dan Biggar kicked 20 points.
Second-half intercept tries from Cobus Reinach and Luther Burrell added gloss to the scoreline, but Saints were deserved winners.
All Worcester could manage were two penalties from Duncan Weir who had an off night.
After Weir put the kick-off out on the full, Northampton dominated the early exchanges and Taqele Naiyaravoro had an early try ruled by TMO Rowan Kitt out for a foot in touch.
The giant wing was tackled under pressure by Bryce Heem, but Biggar rewarded his team's impressive start with two penalties either side of a simple miss from his opposite number.
Weir had kicked 19 straight attempts going into this game, but he somehow skewed a simple attempt wide of the posts early on.
Saints' attacking intent was clear in the opening quarter, Biggar spreading the ball wide from his own 22 where Tom Collins sped away down the right wing.
And when scrum-half Reinach ripped the ball from GJ van Velze, Biggar made it 9-0 to the Saints with his third kick of the night.
The home crowd were far from happy with referee Wayne Barnes, but he did penalise Burrell for a high tackle which allowed Weir to put Worcester on the scoreboard.
Biggar put a drop goal wide and Tom Wood's charge down of a Francois Hougaard box-kick bounced dead, but Saints turned around 12-3 ahead.
Biggar's fourth penalty and a second miss from Weir had left Worcester with plenty to do.
Saints had a 100 per cent tackle success before the break, but Worcester's only comfort was their impressive scrum. Weir narrowed their deficit to six when the game resumed, but even though they were improved in the second period, things just did not quite go their way.
Josh Adams chased down a kick ahead, but it ran away into touch when a kinder bounce would have led to an almost certain try.
Then, Worcester turned the ball over in a prime attacking position. Biggar led the Northampton riposte by superbly claiming an up and under, but he was forced from the field with Wood after both suffered blows to the head.
Worcester pounded away in search of a try using their scrum, but as they pushed on their opponents' line, Hougaard saw his pass intercepted by opposite number Reinach.
The scrum-half ran the length of the field to score the game's decisive try. Piers Francis converted with Biggar absent to put Northampton in the driving seat.
There was still time for Biggar to return to the field and kick two more late penalties before Burrell intercepted following a poor Weir pass.
Biggar rubbed salt in opposition wounds with the conversion on a night to forget for Worcester.