Jamie Elliott ended his try drought in style as Saints survived a second-half scare to beat London Irish 36-21 and cement their top-two spot.
Elliott, who had not scored since the win against Bath on December 28, grabbed two first-half scores to set Saints on their way to a bonus-point success.
Kahn Fotuali’i, Salesi Ma’afu, with his first Northampton try, and Alex Waller completed the victory for Jim Mallinder’s men.
But it was not without nerves as Irish scrapped their way back from 29-0 down to make things tense in the final 20 minutes.
Quickfire tries from Andrew Fenby, Shane Geraghty and Jebb Sinclair gave the spirited away side real hope of earning unlikely points from the encounter.
And, with Waller in the bin late on, Saints had to ride out the storm, with Marland Yarde’s try disallowed for a forward pass in the build-up.
Waller added a final flourish, though, as Saints moved seven points clear of Bath and Leicester in the race for a home play-off semi-final.
The victory ended a run of three successive league defeats, with the home side rewarded for what they had done in the first 55 minutes of this game.
George Pisi set the tone for Saints, giving Geraghty a warm welcome back to the Gardens with a sledgehammer hit, drawing groans from the home faithful.
It also issued a retort to Irish, who had started with the bit between their teeth, and Saints moved into the opposition half to win a penalty, which Stephen Myler landed.
It got the scoreboard moving and Saints didn’t have to wait long to add to their tally as Fotuali’i’s box kick deflected into Elliott’s path and he raced clear to score.
Elliott scored a hat-trick in the corresponding fixture last season and he used this one to end a near four-month tryless streak.
Myler, who was to finish the day with nine points to his name, added the extras and Saints had a 10-0 lead inside the first 15 minutes.
Geraghty threatened to issue a quick riposte as he ghosted through a weak Ben Foden tackle before eventually being hauled down, with Saints managing to clear.
At the other end, Irish were not doing so well in clearing their lines and after Phil Dowson charged down Tomas O’Leary’s kick, Fotuali’i made the most of a kind bounce to score.
Myler landed the conversion, with some assistance from the crossbar, and Saints were in command.
And they were to take an even tighter grip on proceedings before the break as Foden’s superb spin and break was followed by some nice hands in midfield, setting Elliott free.
The wing’s score was added to by another fine Myler conversion, giving the home team an imposing 24-0 lead as the teams trotted off the pitch at the break.
Saints immediately went for the jugular as they emerged for the second half, with a rapid attack finished by Ma’afu, who latched onto Myler’s pass to the delight of the home fans.
The popular Australian’s first Saints try was followed by an unusual miss from Myler, but Mallinder’s men 29-0 up with more than 35 minutes to play.
Irish kept plugging away and eventually had some reward as Luther Burrell failed to clear, instead kicking the ball into the path of Fenby, who scored.
Geraghty grabbed the conversion and he soon had a try to his name as some sloppy play from Saints allowed him to race away unchallenged.
The fly-half added the extras and suddenly Irish were sensing the chance to grab an unlikely point from the game.
The scent got even stronger soon after as Waller was sin-binned and Irish used their man advantage with quick effect as Sinclair charged over.
Geraghty cut the gap to eight points with 11 minutes to go and Saints were suddenly clinging on.
Marland Yarde looked to have made things even more uncomfortable as he raced clear, but his try was chalked off for a forward pass from Tom Homer.
And Waller ensured Saints would have the final say, charging over in the corner, with James Wilson converting with the last kick of an enthralling encounter.
Saints: Foden (Wilson 62); Elliott, G Pisi, Burrell, North; Myler, Fotuali’i; A Waller (E Waller 55 (A Waller 65)), McMillan, Ma’afu (Denman 55); Manoa (Clark 40 (Williams 63 (McMillan 69))), Lawes; Dowson, Wood (c), Dickinson (van Velze 60 (Ma’afu 69)).
Replacements not used: A Day, Hooley.
London Irish: Lewington (Homer 45); Yarde, Mulchrone, Sheridan, Fenby; Geraghty (c) (Dorrian 75), O’Leary (Allinson 45); Parr (Harris 70), Mayhew (Hagan 47), Halavatau; Low (Evans 33), Rouse; Cowan (Sinclair 50), Ellis, Treviranus.
Referee: JP Doyle