The villagers, who last won the title in 2008-09, were 180 all out with five balls to spare as opener Ben Fair scored a patient 63 from 101 balls while man-of-the-match Graeme Tryon added a brisk 48 from 47 balls.
Stevie Smith and Indika Senarathne were the outstanding bowlers for NTOB, taking 3-28 from 10 overs and 1-22 from as many overs.
Liam Rukuwai was wicket-less but among the frugal ones.
Priest told his men between innings not to leave anything in the tank.
In reply, the George Diack-captained NTOB could only muster 151 with 12.2 overs still in the bank and Havelock adding 27 extras to the chase.
They got a robust start from opener Josh Paerau (25) Rukuwai (17) but the middle order left their spine at home.
Tail-enders Seb Burrow (28) and JK Whyte (24) gallantly dug their toes in but the competition's leading wicket taker, Jeremy Ketel nailed Burrow and No11 Cory Hamilton (duck) to put NTOB out of their misery.
Tryon took 4-24 from 10 overs, including a maiden, while Ruan Markram took 3-39 and Priest (1-23) was in the miserly corner.
"Graeme is our absolute super star and the rest of us are just club players," said Priest, proud of the entire 14-member squad who are helping the club rebuild with new committee members, coaches and managers.
Havelock North were anticipating a 270-280 total but when they got 180 they thought they had a chance if they bowled like demons.
Early wickets were on the agenda but NTOB got off to a flier.
Priest chucked the ball to Markram, showing confidence in bowler who was "loose" for the most of the summer.
He didn't let him down although Priest deemed it a spinner's wicket.
It was that sinking feeling for Diack and his men who lost the NZ Club Championship final qualifier to The Station Napier Old Boys' Marist.
Rushing off to NTOB's prize-giving ceremony, he said it was a lesson for his younger players who would "become bigger players".
"You've got to lose sometimes to learn and win.
"When you get to the big games we do what we do [lose] and it's a pain in the [butt]."
Diack said NTOB, who are overall, 40-over and 55-over champions, didn't do anything wrong "but no one wanted to take it today by the horns".
He said all the team's dominance and victories throughout the season didn't count for anything come playoff time.
"The Black Caps may not be the best team in the world but they could win one game on their day."
Whyte, who couldn't hold a bat for most of the summer, was unbeaten on 24 but Diack said they couldn't leave that responsibility on the tail end.
"We had pressure put on us and we didn't respond to it in the right way."
