Coach Ryan Martin's team played an attacking brand of rugby to score 13 tries to beat arch rival King's High School 79-6.
It was the biggest winning margin and beat the 68-0 win of 1983.
It was also the highest winning score and beat the 71-7 win of 2001.
King's was competitive for the first 20 minutes, when Otago Boys' led 12-6, but the floodgates opened when lock Josh Dickson charged down a chip kick by King's first five-eighth Mackenzie Haugh and dashed 50m to score under the bar.
It took time for Otago Boys' to get its game going but that try was the turning point in the game.
It added two more tries, to lead 31-6 at the break. It was one-way traffic in the second half, as Otago Boys' spread the ball wide to score eight more tries.
Dickson gave Otago Boys' domination in the lineout and its superior scrum kept the team going forward.
Tighthead prop Jermaine Ainsley was powerful on the drive and made ground with the pick and go. No 8 Alex Fitzgerald used his strength to break the advantage line.
The Otago Boys' pack was a polished machine and important features were the speed with which it recycled the ball at the breakdown and the support play by the forwards.
This sustained the momentum, tested the King's defence, and opened up gaps for the tries. The forwards ran like backs.
Otago Boys' had the game in its grasp at halftime but coach Martin was not satisfied.
"No tries," was his call and the team responded with desperate tackling in the final minutes, when the King's forwards put together 15 phases and attacked inside the Otago Boys' 22m.
This final foray into Otago Boys' territory was a tribute to King's tenacity. It refused to give up.
Other players to impress for King's were No 8 David Taua, who made ground with the ball, and long-passing halfback Kereama Joseph Te Huki.
Key Players
The top four
Troy Callander: The Otago Boys' captain and blindside flanker was aggressive at the breakdown, tackled ferociously, made ground with the ball and scored three tries.
Josh Dickson: The big Otago Boys' lock dominated the lineout and made nine clean takes, was mobile around the paddock and scored a runaway try from 50m that broke up the game.
Aleki Morris: The Otago Boys' midfield back played with maturity, ran strongly with the ball in hand to set up his outsides and scored a try.
Ben Johnson: The Kings captain and openside flanker was skilled at the breakdown, tackled his heart out and never gave up.
OBHS v Kings
The scores
Otago Boys' ... 79
Sekonaia Pole, Jermaine Ainsley, Josh Dickson 2, Troy Callander 3, Matt Ellis, Eti Slater, Aleki Morris, Josh Dawson, Ben Miller, Lisala Halaleva tries; Sam Ellis 4, Sio Tomkinson, Ben Miller 2 cons)
King's ... 6
Mackenzie Haugh 2 pen.
Halftime: Otago Boys' 31-6.
Crowd: 3200.
