Karly Heffernan of St. Albert, Alta., scored 58 seconds into overtime Saturday to lift the Canadians to a thrilling 2-1 victory over arch-rival United States.
The victory came after some nailbiting moments in the Canadian dressing room before the overtime period.
Catherine Dubois of Quebec City gave Canada a chance at victory when she scored with just 13 seconds left in regulation to send the game into an extra period.
"We were pretty shaken, we were really happy, and we needed to calm down for the overtime," Heffernan said.
The Canadians cemented the victory when Hanna Bunton of Belleville, Ont., fired a pass from behind the net that Heffernan one-timed.
"It was definitely the biggest goal (of my career). I can't even remember half of it, it's crazy," Heffernan said laughing.
Canadian coach Jim Fetter said he spent the break before overtime reassuring his team.
"We just talked about the process and what our goal was here, and a couple of other words in there," Fetter said. "Just that they were good and for them to believe, that we were in great shape ... just kind of built them up and let them know that as a staff we were calm as well and we believed in them and that it only took one shot.
"And obviously that's what happened."
Jennifer Ryan scored for the U.S. scored ath the 18:04 mark of the first period, as the Americans pelted Canada's net through a shaky first period that saw the U.S. outshoot the defending champions 20-1.
"We didn't get a very good start, they kind of took it to us in the first period and we had great goaltending by Kimberly Newell," Fetter said. "We just talked to the girls about sticking to the plan and use our conditioning and I think that's the one thing is we were in pretty good shape and we were able to keep rolling lines and putting all kinds of pressure on them."
Newell, a native of Burnaby, B.C., stopped 39 shots while American goalie Sidney Peters made 23 saves.
Canada defeated the U.S. 3-0 in last year's final.
The two teams have dominated the event, meeting in the final at all five previous world championships. The Americans won gold on three occasions, while Canada's third title came in 2010.
"We knew this was going to be a big rivalry going into it, we knew both teams were very strong, but as a team I think we stuck together," said Canadian captain Kristyn Capizzano. "We knew what we were capable of doing and I think that's what made us reach our goal here."
Canada had beaten the U.S. in a three-game series this past summer, splitting the first two games before clinching the third game in a shootout.
"I wasn't expecting anything different here," said Fetter, who was an assistant with the team that won gold last year. "I think the girls believed in that as well and just kept working hard and obviously came out on the right end of the stick here."
Canada finished atop Group A of the preliminary round with a 3-0 record, outscoring its opponents by a 15-1 margin.
The Americans won Group B with an identical record but scored 25 goals while allowing none during the preliminary round.
The U.S. was the first team in tournament history not to allow a goal during the preliminary round.