Gloucester, looking to regain top spot following Leicester's win over Bristol on Friday, surged into a 14-0 lead at Franklin's Gardens thanks to tries from Max Llewellyn and Will Joseph.
But Tom Pearson and Curtis Langdon drew Northampton level by half-time.
The hosts had to wait until the final quarter to pull clear, the in-form George Hendy adding a third try for Northampton before Rory Hutchinson's late score put the result beyond doubt.
Victory left Northampton third in the 10-team table, with the Saints one of four teams on 16 points - five behind leaders Leicester.
Saracens returned to winning ways with a hard-fought 39-31 bonus-point success at home to Newcastle.
It appeared Sarries were heading for a second successive league defeat, following last week's London derby loss to Harlequins, when Newcastle led 17-7 at half-time.
But fledgling England wing Noah Caluori came off the bench to race over for one of Saracens's five second-half tries.
Newcastle scored four tries but none came from Christian Wade, with the veteran wing still searching for the score that will break the all-time Prem record of 102 tries he currently shares with the retired Chris Ashton.
"It will come eventually but he just has to be patient," said Newcastle boss Dan McFarland. "He didn't get many chances today."
Harlequins backed up their win over Saracens with a 31-28 win at Exeter.
The visitors led 14-0 after 11 minutes but gave away nine penalties as Exeter fought back to leave the match level at 14-14 come half-time.
Quins tightened things up after the interval, with coach Jason Gilmore saying: "I don't think we gave away a penalty again until the last minute of the game, when we went back-to-back and the boys gave me a bit of a heart attack, but I am really proud of them."
Bath put their defeat by southwest rivals Gloucester behind them with a 38-26 bonus-point win at home to Sale.
Joe Cokanasiga scored two of Bath's tries, with Henry Arundell, Tom de Glanville and Louie Hennessey also crossing for the hosts at the Rec.