Travis Konecny added a pair of goals while Jansen Harkins, Mathew Barzal, Lawson Crouse, Adam Musil, Mitchell Stephens and Tyler Soy added singles for Canada, which reached double digits in goals in a summer under-18 game for the first time since 2000.
"I thought our guys played hard and we were ready to go off the hop," said head coach Jody Hull.
Canada will play the co-host Czech Republic in Saturday's final at Breclav. The Czechs defeated Sweden 4-3 in the late semifinal.
"We've got to go out and play our game," Hull said. "If we can go out and play our game for 60 minutes, that's going to be the key. You've got to be ready for anything.
"So we're just going to enjoy this tonight and be focused and ready to go tomorrow."
All but two of Canada's 18 skaters recorded at least a point in the blowout victory and Zach Sawchenko made 24 saves.
Thomas Novak scored twice for the Americans. Brock Boeser, Tanner Laczynski and Ryan Moore had the other goals.
Canada finished first in Group B in preliminary round play with a 3-0 record while the Czechs led Group A at 3-0. Sweden and the United States will play for the bronze medal on Saturday.
Canada has won this tournament six years in a row, and 18 of the past 23 times since it began in 1991.