Their undefeated season unravelled in the second half of the women's club final at Forsyth Barr Stadium on Saturday.
University had more left in reserve and pulled away to win 32-19.
Halfback Rosie Kelly was one of the stars. She dotted down once and slotted a couple of conversions and a penalty.
But it was the lift she provided around the paddock which helped propel University to the title.
"We're a second-half team and we knew we had the fitness on them," Kelly said.
"But we just needed something to spark it and I took that on myself.
"We're so stoked. They put in a massive effort and it was an awesome game."
Pirates scored twice in the opening 15 minutes and threatened to run away with the final.
The pack was crashing on to the ball hard and getting across the gain-line all too easily.
Loose forwards Cristy Watkins and Vanessa Macdonald were making plenty of metres, and midfield combination Greer Muir and Kilisitina Moata'ane were punching holes in the defence.
First five-eighth Sheree Hume was constantly getting through half gaps and eventually the defending champion cracked.
Moata'ane crashed over and a few minutes later a nice run from Muir laid the groundwork for lock Michaela Day to slide over.
But University stormed back into the contest through some enterprising rugby.
Kelly made a dart along the sideline and chipped ahead. A few phases later, winger Trisha Hopcroft got a lovely in-pass away to Bree Thomas, who went over.
Thomas returned the favour moments later when she got a pass of her own away and Kelly scored close to the posts.
Both sides scored another before the break in a entertaining half.
Pirates held a 19-17 advantage but that disappeared early in the second spell, when Tegan Hollows put her side ahead for the first time.
Fullback Meg Breen struck to stretch the gap to 10. She palmed off one defender and slipped through another tackle in nice run from inside the 22.
Pirates went searching for points and spent some time camped in University's half. But the students defended with tenacity and grabbed some crucial turnovers.
And when it got back down the other end, Kelly slotted a penalty with five minutes remaining, to stretch the lead to 13 points.
University got to celebrate by watching the men's team go back-to-back, as well.
Women's final
University 32 Tegan Hollows 2, Bree Thomas, Rosie Kelly, Meg Breen tries; Kelly 2 con, pen
Pirates 19 Kilisitina Moata’ane, Michaela Day, Sheree Hume tries; Hume 2 con
Halftime: 19-17 Pirates
