Cameron Holding, Mark Matthews and Curtis Dickson also scored for the Canadians, who built a 7-2 lead after three quarters before the Americans scored three times in the fourth.
Kevin Leveille led the United States with a hat trick, while Rob Pannell and Jesse Bernhardt also scored.
It's only the third time Canada has won the field lacrosse world championship with the Americans winning nine since the tournaments inception in 1967.
The United States went undefeated through round-robin play — including a 10-7 win over Canada in the tournament's opening game — to enter the playoffs as the top seed.
Earlier Saturday, Miles Thompson and Randy Staats had three goals each as the Iroquois Nationals downed Australia 16-5 in the bronze-medal game.
Lyle Thompson, Zach Miller and Mike Lazore had two goals apiece for the Iroquois, who were playing in the world field lacrosse championships for the first time in eight years. The Iroquois were unable to participate in the 2010 tournament In Manchester, England, after the British government refused to recognize their travel documentation.
Jerome Thompson, Vaughn Harris, Cody Jamieson and Roger Vyse also scored for the Iroquois, a team of First Nations players from the United States and Canada.
Anson Carter had four goals for Australia, while Nigel Morton also found the back of the net.