No. 4 Western will now meet No. 2 McGill in Sunday's final in a rematch of the Queen’s Cup. The Mustangs lost that game 4-1.
The Redmen booked a spot in the final earlier in the day, despite a 4-3 loss to the No. 3 Saskatchewan Huskies in the other semifnial. McGill advanced thanks to a better goal differential.
Jason Furlong’s short-handed goal at 17:48 of the first period stood up as the eventual winner for Western. The Mustangs had a 3-0 lead after the first period, with Dominic De Sando also scoring in the frame.
New Brunswick scored twice on the power-play goal in the third period on goals by Jon Harty and Kyle Bailey, but couldn't complete the comeback.
Earlier on Saturday, Huskies captain Kyle Ross scored the game-winner during a power play with five minutes remaining in regulation.
The second-seeded Redmen could afford to lose to the Huskies by two goals or less and still qualify for the championship match. The OUA champions had doubled the Moncton Aigles Bleus 6-3 on Thursday, while Saskatchewan lost 5-1 to Moncton on Friday.
The three teams finished Pool B with identical 1-1 records but McGill advanced on a goal differential.
It's the Redmen's second straight appearance in the gold medal game. They dropped a 4-0 decision last year to UNB.
Kyle Bortis had a goal and two assists while Derek Hulak and Cory Smuk also scored for Saskatchewan.
Netminder Ryan Holfeld of Leroy, Sask., delivered a 40-save performance for the Huskies.
Captain Evan Vossen, Francis Verreault-Paul of Mashteuiatsh, Que., and defenceman Keven Dupont of St-Charles-de-Bellechasse, Que., had the goals for McGill.
Morin, a native of St-Georges-de-Beauce, Que., turned aside 26 of 30 pucks fired his way.