Otago left its best performance to last when winning the southern zone championship in Timaru over the weekend.
It will now go on to play Northland in the national final on Saturday.
After going through the round-robin section unbeaten, the Otago Whalers faced home side Aoraki in the final at Alpine Energy Stadium.
It was one-way traffic from Otago, as it ran out a comfortable 38-6 winner.
It led 24-6 at halftime and was never challenged by Aoraki, which quickly ran out of steam.
Otago proved to be the best of the four sides at the championship.
It opened the weekend with a convincing 42-18 win over West Coast.
It backed that up with a 24-20 victory over Aoraki on Saturday afternoon.
Otago then put on a good performance to beat Southland 35-12 on Sunday morning after Aoraki had defeated Southland 24-20 in a key match on Saturday.
Otago went into the final with plenty of confidence and jumped out of the blocks when Jake Fowler scored the opening try after a typical blockbusting run.
Otago scored three more tries in the first half, winger Piliu Tavake getting on the end of a breakdown the right edge to score a classy try.
Big centre Sione Fa’aoso was rampaging at times and was difficult to stop with the ball in hand.
Aoraki offered little resistance and, although it had some ball in the second half, could not get across the line.
Otago coach Dave Reedy said the side put on its best performance of the weekend in the final.
He said the team was scratchy on Saturday but was better in all facets in the final.
“We completed our sets throughout the game and our attack was a wee bit better.
“We stiffened our defence in the game too,” he said.