The match started under clear skies but was delayed at 4-all in the first set while the retractable roof at Rod Laver Arena was closed with the temperature approaching 100 degrees Fahrenheit (38 Celsius).
After winning a tight first set that included one service break each, Kvitova dominated in the cooler, indoor conditions and won seven of nine games after the roof was closed.
It's the first time the 28-year-old Kvitova has made a Grand Slam final since winning the title at Wimbledon 2014.
She missed the Australian Open in 2017 while she was recovering from knife injuries to her left hand suffered in a home invasion home invasion in the Czech Republic in late 2016.
In the men's doubles semifinals, John Peers and Henri Kontinen defeated Leonardo Mayer and Joao Sousa 6-1, 7-6 to advance to the final to face Nicolas Mahut and Pierre-Hugues Herbert after the fifth-seeded French pair ousted Americans Sam Querrey and Ryan Harrison 6-4, 6-2.