Harbour had plenty of opportunities to make the shield its own. First five-eighth Logan Allen had two dropped goal attempts deep in extra time and had two conversion attempts hit the post during regulation time.
University went into the game as favourites and led 16-10 at halftime. But the students needed a late try to force extra time.
Neither side was able to add to the score in 20 minutes of extra time. The tiebreaker was the most tries in the game but with four apiece the title has to be shared.
It is Harbour's first premier banner, while University now has 50 to its name.
In the premier colts finals, University beat Kaikorai 21-19 in a tight encounter, while Dunedin upset West Taieri 20-17 in the premier 2 final.