Jessica Pegula was the highest remaining women's seed left in Melbourne at three, but the hotly tipped American simply had no answers to Azarenka's pounding forehand groundstrokes.
The Belarusian Azarenka, whose two Australian Open titles came in 2012 and 2013, rolled back the years in a surprisingly one-sided quarter-final to triumph 6-4, 6-1.
The 33-year-old is back in the last four in Melbourne for the first time since her 2013 victory.
"Well, it hurts to beat her because I always want her to do well," the 24th seed said of Pegula, a close friend and practice partner.
"I am very proud that I executed my game plan really well," added Azarenka, who had put on a Paris Saint-Germain football shirt.
"So amazing to be in another semi-final of a Grand Slam," said Azarenka, admitting that playing at the 15,000-seat Rod Laver Arena had been "nerve-wracking".
Asked how her young son Leo would receive his mum's latest achievement, Azarenka said: "He's more worried about his football and when we're going to play again.
"He definitely wants his mum to be home."
Leo will have to wait at least a few more days because Azarenka faces Moscow-born Kazakh Rybakina on Thursday for a place in the final.
Rybakina blasted her way into the semi-finals with a ruthless 6-2, 6-4 win over Jelena Ostapenko.
The 23-year-old Rybakina sent down 11 aces to blow former French Open champion Ostapenko off court in 79 minutes.
The 22nd seed has blasted 35 aces so far, more than any other woman at the tournament.
Ominously, she said her serve is better now than when she won Wimbledon last year.
"I gained even more power. It's my weapon on the court and of course we are trying to work on it," she said, before adding: "Always a lot to improve."
- Korda heartbreak -
In the men's draw, the quarter-final between Russia's Khachanov and Sebastian Korda had been warming up nicely until the American hurt his wrist.
The 18th seed went through when Korda retired in the third set, down 7-6 (7/5), 6-3, 3-0.
Khachanov's reward is a clash with either Greek third seed Stefanos Tsitsipas or unseeded Czech Jiri Lehecka, who play later, for a spot in Sunday's final.
Tsitsipas is the highest remaining seed in the draw after a series of shock exits.
The 22-year-old Korda, who had been attempting to emulate his father Petr's Australian Open victory in 1998, said afterwards that he could barely hold the racquet.
He said he first felt the injury while playing the Adelaide International this month, where he made the final and forced a championship point before being beaten by Novak Djokovic.
But it had not bothered him in the opening four rounds at Melbourne Park until he hit a return in the second set.
"I had it in Adelaide and then it went away completely. Now it just came back out of nowhere," he said. "I have never had any wrist issues before.
"I knew kind of what it was right away, right when I hit the return. I kind of felt that spot that I was feeling before.
"Some forehands I couldn't even hold the racquet. Volleying was almost impossible for me, so it was a little tough."
For Khachanov it is a second consecutive Grand Slam semi-final, having reached the last four at the 2022 US Open.
Nine-time Melbourne champion Djokovic is still on the scene, with a quarter-final against Russian fifth seed Andrey Rublev on Wednesday.
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