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Kostyuk had beaten top 10 players Jessica Pegula, Mirra Andreeva and Amanda Anisimova on her way to the final but was no match for the sheer power of the US Open champion.

Sabalenka is determined to win back the Australian Open title she relinquished last year and her performance in the fierce Brisbane heat, suggests she will be hard to beat at Melbourne Park this month.

"Thank you to my team for handling me. I'm really the toughest one to handle, and you guys are the toughest people in the world if you can handle me," she told the crowd before directing a comment at partner Georgios Frangulis in the stands.

"Thank you to my boyfriend. Hopefully, soon I'll call you something else, right? Let's just put a bit of extra pressure on, right?"

Sabalenka raced off to a 3-0 lead in the opening set before coming a bit unstuck as her first serve deserted her and her 23-year-old opponent feasted on her second.

There were the familiar hangdog expressions as Sabalenka raised her eyes to the skies in reaction to spraying a shot high and wide, but it did not last for long.

Rallying at 3-3, Sabalenka reduced the number of wild swings and heaped the pressure on her No.26-ranked opponent with the sheer power and accuracy of her strokes.

She quickly wrapped up the opening set and was soon 3-0 up in the second after again taking Ukrainian Kostyuk's first service game.

There was no way back for Kostyuk this time and she faced a real battle just to hold her serve three times before Sabalenka served out to secure her 22nd WTA title, sealing the deal when her opponent netted a return on her first championship point.

Kostyuk, who refused to shake Sabalenka's hand at the finish because of her Belarusian nationality, said her thoughts were with the people back home in her war-torn country, with Belarus allied with Russia in the conflict against Ukraine.

"I play every day with a pain in my heart and there are thousands of people who are without light and warm water," she said.

"Right now it's minus 20 degrees (celsius) outside, so it's very, very painful to live this reality every day. It's very hot here in Brisbane, so it's difficult to imagine this, but my sister is sleeping under three blankets because of how cold it is at home."

Sabalenka will be gunning for a third Australian Open and fifth Major title at the year's first grand slam, which starts on 18 January. She said in response to the handshake snub she had nothing to prove.