The Belarusian world number two proved too powerful for the 12th seed with a 6-3, 6-2 drubbing in 76 minutes to claim her second Grand Slam crown on Rod Laver Arena.

It capped an incredible display of power and poise from Sabalenka over the past fortnight, with the 25-year-old surging to the title without losing a set through her seven matches.

The last time the tournament witnessed a successful women's title defence was in 2013, when fellow Belarusian Victoria Azarenka achieved the feat.

"It's been an amazing couple of weeks and I couldn't imagine myself lifting this trophy one more time," Sabalenka said.

"I want to congratulate you Qinwen on an incredible couple of weeks here in Australia. I know it's really tough to lose in the final but you're such an incredible player.

"You're such a young girl and you're going to make many more finals and you're going to get it."

With her latest exploits, Sabalenka cemented her reputation as one of the game's most consistent contenders at Grand Slams, reaching at least the semi-finals in her past six majors, making three finals and winning twice.

In vivid red, she overwhelmed Zheng with her crushing groundstrokes deep into both corners and a consistently reliable serve.

Zheng had reached her first Grand Slam final without meeting a seed after a host of players crashed out early on her side of the draw, and the gulf in class was quickly exposed.

The Belarusian opened with a comfortable serve then got a look at two break points at 15-40 in Zheng's opening service game when the Chinese star sprayed a backhand wide.

She seized the chance, attacking her opponent's second serve for the break.

Sabalenka consolidated on serve for 3-0, but only after saving three break points as Zheng's nerves settled and she worked to get into the contest.

The Chinese star finally got on the board as her serve hit its mark in game four, with two big unreturnable aces and a forehand winner giving her confidence.

But she had few answers to the booming Sabalenka serve, struggling to get the ball back over the net and into any rallies.

Zheng saved three set points with a pair of aces and a winner to hold for 3-5, but it was delaying the inevitable as Sabalenka closed out the set on serve in 33 minutes.

Three double faults, including on break point, immediately put Zheng on the back foot on the second set as the pressure took its toll.

And there was no way back as she conceded another break to slump 4-1 behind when Sabalenka prefectly played a drop shot.

Fighting until the end, Zheng saved four championship points before the second seed closed out the match to bank her 14th career title.

Despite the loss, it has been a breakthrough tournament for Zheng, who will move into the world's top 10 when the new rankings are released next week.

"It's my first final and I'm feeling a little bit pity, but that's how it is," said Zheng. "I feel very complicated because I could have done better than I did in this match."

Sabalenka will remain at number two behind Iga Swiatek, who crashed out in the third round.