Northern's imposing total of 184 for seven was plenty at Seddon Park in Hamilton as bottom-placed Canterbury collapsed to 113 all out in the 16th over.
It left just four competition points between the top-four sides, with Otago and Central Districts on 20 and Auckland and Northern on 16 as they chase a spot in the January 31 final, with the next round to be played on Friday.
While Daniel Vettori produced another fine all-round performance, left-armer Bradley Scott was the main bowling destroyer for Northern with figures of three for 11.
Scott's initial two-over spell of three for none crippled the Canterbury innings to 51 for five in the eighth over, after Sri Lankan import Tillakaratne Dilshan took a brilliant catch off Brent Arnel to remove captain Peter Fulton for five.
All three of Scott's victims were key wickets - Shanan Stewart for one, topscorer Rob Nicol for 31 and Craig McMillan for nought - which left Dean Brownlie needing to negotiate the hat-trick delivery.
Brownlie and Carl Frauenstein hit quickfire 20s in a losing cause before both were removed by Vettori who mopped up the tail with figures of three for 31.
Vettori led the way with the bat at No 3 for Northern with a brisk 49 off 41 balls before he was run out in the final over.
All the Northern top-six chipped in, with Anton Devcich continuing his big hitting with four sixes in his 17-ball knock of 35, and Dilshan scoring 28 off 19 at the top.
Andrew Ellis was the clear pick of the Canterbury bowlers with three for 32 off four overs.