Sweden and Australia were drawn in the same group and met in the second group match.
Where it was a Swedish victory with 4-2.
Today's semifinal was initially even where two teams tried to find the right in the attacking game.
Sweden managed to find the surfaces on the edge and they created two quick corners early - which did not lead to a dangerous finish.
With 23 minutes played, the visitors broke through on the right after some poor defending.
Australia, which is coached by Swedish Tony Gustavsson, took over in the final stages and created some dangers.
The closest to a goal was Sam Kerr who had a ball in the net that was disallowed when the referee blew off before.
Dream start
Sweden then got a real dream start in the second half.
After just a few seconds, Fridolina Rolfö reached the top with her foot on a rib return and put it 1-0 at the far corner.
Her third goal this Olympic tournament.
Yellow-clad Australia gave hope to striker Sam Kerr, who both threatened deep and tore in the press game.
After 73 minutes, 18-year-old Hanna Bennison was substituted.
Shortly after the change, Australia got a good goal chance but Hedvig Lindahl covered well at the first post.
Australia forced at the end and created a lot of dangers but the ball never found its way into goal.
With one minute left, Australia received a red card after a player pulled down a free Lina Hurtig.
Sweden held off and could at the final signal celebrate another Olympic final.
The Olympic final will be Sweden's second in a row when they also got there in Rio 2016.
In the final, Canada is waiting, which earlier today beat the USA in its semifinal.
CLIP: Canada ready for Olympic final - after thriller against USA (August 2)
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Jessie Fleming's penalty goal took Canada to the Olympic final.
Photo: Henry Romero / Reuters / Bildbyrån