In the morning, Otago beat defending champion Bay of Plenty 5-3 and, in the afternoon, headed Eastland (formerly Poverty Bay-East Coast), winning six games and halving another.
The afternoon margin of 6-1 proved crucial as Otago was tied on eight points with Waikato but finished first on a countback of games.
In the morning, Otago No 1 Inia Logan suffered his first loss, going down to Bay's Harry Hillier on the 16th green.
But Sungwoo Han, Harry Smith and Jakob Bleach put Otago back in front with 2 and 1 wins over their Bay opponents.
No 5 Connor Ross lost to Byron Willis on the final green but the final two under-16 players ensured the win as Jack Turner and Joseph Hancock posting wins by a margin of two.
In the afternoon, No 8 Hancock was the first to finish with a resounding 8 and 7 win at the expense of Eastland's Reef Pohatu.
Hancock (13) set up his win holing out with his hybrid club for his maiden hole-in-one on the 155m par-3 eighth hole.
His round included two eagles and two birdies for his best performance of the tournament.
Under-16 players Turner and Callum Judkins posted valuable wins and Otago looked set for a team win when Ross dominated Taine Lincoln, winning on the 13th green.
Smith and Han both had comfortable wins but the pressure went on No 1 Logan as the game tally looked like being the decider.
In a close tussle, Logan halved with Eastland's Nathaniel Cassidy, giving Otago an extra cushion in the game countback.
