Despite another defiant performance from rank outsiders Wests, they could not match the firepower of the Devils, who will go in search of a fourth straight premiership against Tweed Heads next Saturday.
Norths, chock-full of Melbourne Storm development players, led 16-6 at halftime but did not seal the game until 14 minutes from fulltime.
The game-turning sequence came when Wests centre Jack Reed beat half-a-dozen defenders only to lose the ball across the line.
A minute later Devils five-eighth Sean Yorston chip-kicked 40m out, with the fullback running past the ball and completely missing it. Yorston regathered and scooped the ball one-handed to a flying Liam Foran in support, making for a 12-point turnaround.
Norths began the game in devastating fashion, forcing an error from the opening kick-off and then stretching the defence for a try to Aaron Hammett in the second minute.
The Devils revisited the same patch of turf on the right flank shortly after and a strong charge by centre Sam Joe had his side up 10-0.
It was smooth sailing for the reigning premiers, who had all the possession and territory until the 12th minute when half Liam Foran kicked out on the full.
The lapse in execution gave Western Districts the ball 20m out and the Panthers made the Devils pay full price, Luke Churchill diving over to close the gap to four points.
But Norths was next to score when Foran started a slick movement to the right, reestablishing a healthy lead as Jharal Yow Yeh crossed in the corner.
The periods either side of halftime featured plenty of fire.