Kellie White, Goergie Parker and Jodies Smith Kenny scored for Australia in the shootout after their captain Madonna Blyth was unable to convert the first try.
Australian goalkeeper Rachael Lynch conceded a goal to Kelsey Kolojejchick, but thwarted Katie O'Donnell, Paige Selenski and Michelle Kasold.
The fifth attempt in the shootout was not needed as Australia had already secured a two-goal advantage.
USA, who came into this tournament ranked No. 10 in the world, twice rallied after falling behind in regulation period to take the contest into extra-time and then into the shootout.
USA made it 1-1 in the 48th minute with a field goal by Kolojejchick, but Australia went ahead again four minutes later through a rasping penalty corner shot from Anna Flanagan.
Pressing hard, USA drew parity again just two minutes from the hooter with Kolojejchick's second open field strike of the semifinal.
Australia, seeking their third World Cup title, now await the result of the second semifinal between defending champions Argentina and 2012 Olympic gold medalists The Netherlands, to be played later today.
