Kvitova reached her first grand slam final outside of Wimbledon with a 7-6 (2) 6-0 victory over surprise package Danielle Collins before US Open champion Osaka made it back-to-back finals by beating Karolina Pliskova 6-2 4-6 6-4.
For Kvitova, the achievement is the latest step in her inspiring recovery from the stabbing by an intruder at her home in December 2016 that nearly ended her career.
The damage to the fingers on her playing hand was so severe that doctors feared she may not play professionally again, while the mental scars were just as deep.
The 28-year-old, who won her second title at Wimbledon in 2014, said: “I’m still not really believing that I’m in the final. I didn’t know even if I was going to play tennis again.
“It wasn’t really a nice time to be dealing with everything. It wasn’t only physically, but mentally it was very tough, as well.
“It took me really a while to believe in the people around me again, and especially men, for sure. I wasn’t confident to be alone somewhere.
“It was a lot of work with the hand, a lot of recovery, treatment. I think the sport life helped me a lot with that. I just set up the mind that I really wanted to come back, and I just did everything.
“Those three months were very, very tough. I found out lately that my doctor wasn’t really happy with my hand during the second month, because the scars were very, very tight and hard, and I couldn’t really do anything with that.
“Luckily he didn’t tell me during that period. It’s been a long journey.
“I’m really happy to be back (in a final) again. I think not very many people believe that I can do that again, to stand on the court and play tennis and play at this level. It was just really a few of them, I think.
“I’m very happy to have those few around me. Definitely it feels great. Hopefully for them as well, for my family and for everybody who was there when I needed it.”
Rafael Nadal attempted to pick Stefanos Tsitsipas’ chin off the floor after ending the run of the exciting young Greek in brutal fashion to reach his 25th grand slam final.
Tsitsipas was looking to become only the third man after Juan Martin Del Potro and Novak Djokovic to beat both Roger Federer and Nadal at the same slam but was firmly put in his place as the Spaniard swept to a 6-2 6-4 6-0 victory in just an hour and 46 minutes.
Nadal, who is yet to drop a set in Melbourne, will take on either Djokovic or Frenchman Lucas Pouille in the title decider on Sunday.
Tsitsipas went into the match full of confidence from his breakthrough fortnight and with the knowledge that he competed well against Nadal in their last meeting in Toronto last summer.
But this was a very different story, and Tsitsipas looked shell-shocked in his post-match press conference, saying: “Honestly, I have no idea what I can take from that match.
“It felt like a different dimension of tennis completely. He has this talent that no other player has. He makes you play bad. That’s definitely not the way I wanted to leave from the tournament.
“I did play a good match in Toronto against him. I had my hopes high for the next time. I remember saying to myself, ‘I’m going to beat this guy next time’. That’s why I’m so disappointed, because I wasn’t even close.”
Djokovic plays Frenchman Lucas Pouille in the second semi-final today.