The United States and Canada have won every gold medal since women's ice hockey joined the Winter Games programme in 1998 and the Americans signalled they are once again ready to challenge for top spot with a clinical victory.
The United States, who chose not to take part in Friday's opening ceremony in order to rest ahead of the game, scored on their first shot, just 53 seconds into the opening period.
Hilary Knight stole the puck and rifled it past Finland netminder Noora Raty to open the scoring.
Kelli Stack and Alex Carpenter added goals in the second period to make it 3-0 before Susanna Tapani pulled a goal back for Finland to spoil US netminder Jessie Vetter's shutout bid with just under five minutes to play in the third.
Only a valiant effort from Finn goalie Noora Raty prevented the contest from becoming a complete rout as the United States outshot Finland 43-15.