The unheralded Pole played wonderfully controlled tennis that belied her ranking of 45th in the world to wrap up a thoroughly deserved victory in the blazing sun on Rod Laver Arena.
Linette had been expected to play second fiddle to compatriot Iga Swiatek at Melbourne Park but will now battle for a place in the final against Aryna Sabalenka.
"It's so much and I can't really believe it," she said. "It's really dreams come true. We keep going, though, I don't want to get too excited because we're still in the tournament, but I'm super grateful and happy."
After both players were broken in their opening service game, Linette showed the greater composure and took control of the first set as twice Grand Slam finalist Pliskova racked up 14 of the 36 unforced errors she would make over the match.
Pliskova knew she had to raise her game in the second set and ramped up the rasping forehands but Linette had the answer to everything the Czech threw at her.
She saved two break points to hold for 2-2 and then earned three of her own on Pliskova's next service game only for the Czech to battle back with a couple of big winners.
The set stayed on serve but Linette appeared to have the upper hand, winning one point with a sublime running backhand crosscourt winner, and she pounced to break for 6-5 when Pliskova offered her two chances with a double fault.
She threw her racket to the ground after serving out nervelessly for the match, clasping her head and staring wide-eyed at her box after reaching the last four for the first time in 30 Grand Slam appearances.
"I will never forget this," she added. "I'm breaking through some really difficult things for me. This will stay with me for life. So I'm really grateful."
Linette had never been past the third round at a Grand Slam before arriving at Melbourne Park this year and said a change in mentality was behind her fairytale run.
"I think through all my life I've been taking mistakes losses very personally," she explained. "So to disconnect (life) as a tennis player and a person was really difficult because I felt a lot of times that the mistakes were defining me.
"My coaches did a really great job and I'm really thankful to them because they really put up with a lot of crap."
Misfiring Serve
Pliskova's serve deserted her at the worst possible time, but the Czech said she would take some positives from her run at Melbourne Park.
"Super disappointed about today, because I just thought this was a match which I should win and I could win," Pliskova, who missed last year's tournament due to an arm fracture, told reporters. "Obviously the serve was not great today at all.
"I suppose you can have days like this. I have been serving really well for like all my matches, and pretty much like for the last two, three weeks."
Pliskova made seven double faults compared to just one from her opponent. The Czech also chalked up 36 unforced errors, more than double Linette's count.
"On the other hand, I think I played some good tennis here," she added. "All the matches were quite good. For sure, some positive things. Just happy to be back in this stage of tournaments. I've got to keep trying."
Pliskova, the 30th seed, had come into the contest with a 7-2 record against Linette but the Pole had beaten her in straight sets in their most recent meeting at the Billie Jean King Cup at the end of 2022.
"I don't think she's much different than she was," Pliskova said. "Of course she improves, but I think the main thing ... is just a belief and the confidence, which obviously she has now.
"I think she really made it like difficult for me, not missing many balls, not giving anything for free, any mistakes.
"I just didn't play a great match. I don't think that it was bad, but definitely I can play better."
