Recovering from a broken collarbone, striker Barclay reversed Roslyn's fortunes when she came on as a substitute in the second half and showed blistering pace and finishing power.
A New Zealand futsal representative who also plays for Otago in the outdoor game, Barclay scored the matchwinner with minutes to go.
The women's game has improved out of sight in recent years, and has arguably generated more commitment, passion and good technique than many senior men's matches have done this season.
Northern started strongly and led 1-0 after 19 minutes when Roslyn goalkeeper Caitlyn Fitchett spilled the ball and Mikaele Garland pounced to score.
Garland struck again only three minutes later when she ran onto a defence-splitting pass from Carena Oosterbaan and shot Northern into what looked like a comfortable 2-0 half-time lead.
In the second half, Roslyn winger Sam Muirhead showed pace before delivering a perfect right-wing cross for Barclay to ram in a headed goal that lifted her side's morale.
Then it was Madden as the provider, setting Barclay free to equalise with 10 minutes to go, and while Roslyn exerted relentless pressure, Northern made several counter-attacks that could have earned a win.
Under huge pressure, Northern keeper Cherie Boucher denied Roslyn with a string of superb saves that included corners and one-on-ones against Barclay and Madden.
In the midfield battle, Elise Mamanu-Gray showed great poise and balance, as she and Kushla Glover battled for supremacy against Monique Francois and Alana Ainsworth.
The breakthrough came after Northern had an offside goal disallowed, and from a perfectly weighted Muirhead pass, Barclay scampered round Boucher and stroked in an angled winner with two minutes to go.
Roslyn coach Marcus Glover was delighted to retain the premier trophy.
"There were some gutsy performances out there playing through injury," Glover said.
"Briony is still coming right from her collarbone fracture, and there were some violent collisions during the game.
"We eventually played to our strengths, turned their defence with some good wing play and crosses and Briony's second half hat trick was a classy demo of top finishing."
In senior men's games on Saturday, Northern bounced back from last week's 9-0 defeat by Dunedin Technical to beat Roslyn-Wakari 3-1 in a game that was a pale shadow of former matches between two of Otago's oldest clubs.
Early Northern pressure came from some runs on the left wing by Tim Smith, and his cross in the 15th minute was driven in by Jason Anson to put the home side ahead.
The equally swift Fraser Cameron equalised for Roslyn.
Northern shocked spectators by scoring twice in as many minutes.
Liam Dungey drilled a penalty past Roslyn keeper Nathan Watt, then the hapless keeper fumbled a long-range shot by Anson.
Mosgiel kept its unbeaten record and remained top after beating Dunedin Technical 4-1, with Mike McGarry and Phil Kelly showing surprising pace to get on the scoresheet.
At Ocean Grove, Grants Braes beat University 1-0.
