Brianne McLaughlin-Bittle stopped all 11 shots she faced for the Americans (2-1), while Shiann Darkangelo picked up two assists.
Sara Grahn made 47 saves for Sweden (0-3), which has yet to score a goal in Kamloops and will play in the third-place game.
"Their goalie played a really great game," said Knight. "She made a lot of really great saves, but it wasn't frustrating for us at all. We're a relentless team."
Canada (2-0) was set to take on Finland (1-1) later Friday in the tournament's final round-robin game. The Canadians will play the U.S. for gold on Saturday unless the Finns are able to score an unlikely victory of 4-0 or more against the hosts.
Finland lost its first game of the tournament 5-0 to the U.S. before beating Sweden 1-0.
In Friday's early game, Knight opened the scoring at 5:12 of the first for the Americans, who had just one goal to show for their 22-2 edge in shots after 20 minutes.
"We just had to continue our energy and keep our momentum," said Knight. "There's unfortunate bounces that can happen here and there throughout a game. Luckily we just stayed on our toes and kept at it."
Grahn held the fort for the Swedes as the game wore on until Pfalzer scored on a 5-on-3 power play at 14:25 of the second to make it 2-0.
Decker then put the game completely out of reach with a nice short-handed effort with 31.7 seconds remaining in the period.
"We had a lot of energy," said U.S. head coach Ken Klee. "Great chances, moving the puck, moving our feet — those are the things we have to pride ourselves in.
"It was a fun game."