Canada is World Junior champions for the second time in just under five months.
Dylan Guenther scored the golden goal in overtime as Canada survived a third-period charge from Czechia to win 3-2 in the final Thursday night in Halifax.
Guenther also scored earlier in the game and Shane Wright got the other goal for Canada while Jiri Kulich and Jakub Kos provided the markers for Czechia.
The tournament hosts led 2-0 mid-way through the third period until two quick Czech goals pulled them even with Canada and eventually forced the extra frame.
The pair met on Boxing Day with Czechia picking up a surprising 5-2 victory. It was the first time Canada lost their opening game of the tournament as hosts.
"We remember the first game," forward Joshua Roy said Wednesday of the rematch, adding he felt the Czechs were "pretty cocky" with how they celebrated.
This was the first time the two teams met for World Junior gold in the tournament's current format, while Canada was 6-0 against Czechia in the medal round all-time coming into the final. Canada is the first team to repeat as champs since they did it in 2009 while Czechia earns their first medal since 2005.
Canada advanced to the final with a 6-2 win over Team USA Wednesday night where Roy had four points and Thomas Milic stopped 43 of 45 shots. Milic won player of the game and called the reaction he got from the fans the “coolest moment of my hockey career.”
Canada got a major scare a round earlier as Slovakia took them to overtime but Connor Bedard saved his team's repeat hopes with an incredible backhand winner. The presumptive No. 1 overall pick in the 2023 NHL Draft finished with the most all-time goals (17) and points (36) by a Canadian at the event and also owns the points record (23) at a single tournament by a Canadian player.
Czechia booked their spot in the gold medal game with a thrilling 2-1 victory over Sweden in the semifinals on Wednesday. The Swedes led 1-0 late into the third period but David Jiricek tied things with 39 seconds to go and then Jiri Kulich scored late in the extra frame to complete the comeback.
Earlier on Thursday, the United States defeated Sweden in overtime 8-7 in a back-and-forth bronze medal game. Luke Hughes completed his hat trick with the overtime winner to give the Americans their fourth medal in the past six tournaments.