The win brings the Otago tally to 14 titles since the inception of the event in 1962.
The most recent successes were back-to-back wins at Balmacewen in 2004 and Oreti Sands in Invercargill in 2005.
A narrow win over Canterbury on Saturday set the scene for the win, along with a 5 to 3 win over Tasman.
After the third round yesterday morning, Otago was tied 2-2 with Aorangi and Southland and had all the work to do in the final round.
A 4.5 to 3.5 win over Aorangi put Otago on three points and a 4-4 draw with Southland sealed the result.
The event doubled as the final trial for the Otago men, and the selectors' task was not made easy when Hamish Ireland (No 5), Thomas Facer (No 6), Simon Hollyer (No 7) and Chris Snow (No 8) all went into the final round unbeaten.
Hollyer and Snow won their final matches for four wins in the event, while Ireland and Facer fell at the final hurdle.
Southland's top juniors acquitted themselves well, with Otago championship winner Liam Balneaves (No 1) and No 3 Vaughan McCall (Gore) posting four wins each.
For Canterbury, Tom Turner (No 4) had four wins while Scott Fox (No 5) and Harry Bateman (No 6) emerged unbeaten with three wins and a half.
Hollyer (Wanaka) will make his debut in the Otago men's team in the Toro National Interprovincial teams tournament on the Paraparaumu Beach course in Wellington from December 7 to 11.
After his performance at the weekend, Hollyer has risen to No 5 in the team, displacing Tyrone Ratahi (Otago), who has been relegated to travelling reserve.
Ireland (Otago) will also make his debut for Otago and will play at No 4.
The top three are experienced campaigners.
Brent McEwan (St Clair) captains the team at No 1, Duncan Croudis (Otago) is at No 2 and Michael Smith (Otago) at No 3.
Croudis had to withdraw from the South Island event due to a family bereavement, and his absence meant team emergency Mitch Bosley (Wanaka) was at No 2 for the weekend.
But selectors Murray and Alan Rose deemed he had too much ground to make up.
Otago team
In playing order
Brent McEwan (St Clair, captain), Duncan Croudis (Otago), Michael Smith (Otago), Hamish Ireland (Otago) and Simon Hollyer (Wanaka).
Travelling reserve: Tyrone Ratahi (Otago).
Manager: Ben Gallie (Millbrook).
