The Tauranga side had first use of the batting strip at Nicholson Field and were dismissed for 160 in the 43rd over.
Sean Dykes top-scored with 56, with Tauranga Boys' bowler Gurwinder Singh compiling a handy 22 runs.
Tim Williams was the pick of the New Plymouth bowlers returning 3/39.
New Plymouth opener Josh Borrell got his side away to a good start with a patient 45. Just when Tauranga Boys' had fought their way back into the match, Sam Morrison arrived at the crease to take them home to victory with an unbeaten 45 runs.
Results
Championship Final
Palmerston North BHS 133 (I Harris 24, M Hughes 22; M Clarke 4/17, B Gaylor 3/28) lost to Hamilton BHS 134/5 (J Gibson 35no)
Playoff for Third/Fourth
Tauranga Boys College 160 (S Dykes 56, G Singh 22; T Williams 3/29, D Mills 2/15, B Lilley 2/38) lost to New Plymouth BHS 161/5 (J Borrell 45, S Morrison 45no; S Wakelin 2/37)
Playoff for Fifth/Sixth - Hastings BHS 71 lost to Napier BHS 72/3
2015 Super Eight Batsman of the Tournament: Jake Gibson (Hamilton BHS)
2015 Super Eight Bowler of the Tournament: Brayden Gaylor (Hamilton BHS)