Glamorgan wrapped up their third County Championship win of the season before lunch on the final day to climb to second place in the Division Two table.
Resuming at 126-4, Northants were bowled out for 193 to lose by an innings and four runs.
James Harris added two scalps to finish with 5-62, taking his Championship tally for the season to 30.
And Jim Allenby weighed in with three wickets, only nightwatchman David Lucas (32) offering any lasting resistance.
It took Glamorgan only 22.5 overs of the final day to seal back-to-back Championship wins for the first time in six years.
Victory came 20 minutes before lunch as Northants lost their last six wickets in the space of 17 overs.
Still needing 71 to avoid an innings defeat when they resumed, David Sales and Lucas looked relatively untroubled in the opening half hour.
But David Harrison broke through in the sixth over with a fine ball which nipped back between bat and pad to knock over Sales' off stump.
That opened the floodgates, Andrew Hall falling leg before to Harris not offering a shot. And then Allenby struck twice in an over to earn two more LBW decisions against Nicky Boje and Lucas.
Lee Daggett lasted just two balls before becoming Allenby's third victim, caught at second slip by Jamie Dalrymple.
James Middlebrook and Jack Brooks looked as if they may avoid the indignity of an innings defeat, putting on 22 for the last wicket.
But Harris had Brooks caught behind to secure a win which now sets up an intriguing clash at Sophia Gardens next week with Gloucestershire, just a point behind in third.
The Glamorgan-Gloucestershire game starts on Monday (17 May) at the delayed time of 1200 BST.
Glamorgan captain Jamie Dalrymple:
"Northants are not a bad side and we won by an innings - that's very pleasing and a tribute to the way the lads are developing.
"Everyone chipped in and that's a very healthy situation, it's looking quite good at the moment.
"I've not been playing badly so it was nice to get stuck in and make a meaningful contribution, but it wasn't just me by any stretch of the imagination.
"The Championship is still the heart and soul of cricket and a great basis for all the other forms of the game.
"We obviously have targets in one-day cricket, but we want to keep improving in the Championship."