The world number one from Belarus, outclassed in last year's final by Elena Rybakina before going on to win a second straight Melbourne Park crown, appeared off the pace against Kudermetova and lost the first set by dropping her serve for a second time.
Kudermetova came under pressure on serve in the opening game of the next set but the aggressive world number 107 rode out the storm and began to dictate play with more heavy hitting from the baseline to trouble Sabalenka.
"That was really great tennis from her," Sabalenka said.
"It was really aggressive. She has some variations and she was using it really well. She definitely deserved to be in the final. I'm pretty sure if she continues working the way she is, then she will be in the top 50 soon."
A delicate drop shot handed Sabalenka the break, and the 26-year-old appeared much more like her usual dominant self in the rest of the set as she forced a decider, much to the delight of fans at a packed Pat Rafter Arena.
Sabalenka offered another reminder of her calibre by breaking in the third set with a sharp cross-court forehand winner and staved off a late comeback attempt from Kudermetova to claim her first title of the season.
She is bidding to become the first woman to lift three straight Australian Open trophies since Swiss Martina Hingis won from 1997 to 1999, and she will head to Melbourne Park brimming with confidence.
"I'm super happy to lift this trophy," said Sabalenka.
"It's a really important tournament before heading into the Australian Open. The final match was a bit tricky, (both of us) were over-hitting.
"I'm really curious about the average speed of our shots. It was a crazy match, and I'm really glad I got this win."
Czech player Jiri Lehecka claimed the Brisbane men's title later on Sunday after Reilly Opelka retired with an injury while trailing 4-1 in the opening set.
The American upset Novak Djokovic in the quarter-final but appeared to struggle with a wrist issue in his semi-final win over Giovanni Mpetshi Perricard.
The 6-foot 11-inch Opelka spent nearly two years on the sidelines due to wrist and hip issues that needed surgery and only returned to the elite circuit last season.
