Avery Lynch scored the KIJHL Cup-winning goal 1:33 into the second overtime, firing a shot past Gibson Horne after it bounced off the boards toward the net to secure the championship for Kimberley.
Luke Davies led the Dynamiters with two goals, while Adam Kisilevich made 38 saves in the title-clinching victory.
The Dynamiters built a 2-0 lead before the Posse rallied to tie the game on goals by Paul Vanden Elzen and Alex Westlund. Jace Shuttleworth also scored for Princeton.
Horne was sharp in goal for the Posse, finishing with 40 saves. Jalen McRae chipped in with two assists.
The Dynamiters had won eight of 11 games when leading after two periods this season.
Coming into Game 7, Kisilevich had a 1.84 goals-against average and a .940 save percentage.
