Andreeva, the 14th seed, was simply unable to get going in the fourth-round clash on Rod Laver Arena as Sabalenka raised her level a couple of notches to extend her winning streak at Melbourne Park to 18 matches.
Sabalenka, who was stunned in three sets by Andreeva in the quarter-finals of last year's French Open, ramped up her serve at any hint of a threat from the 17-year-old and wrapped up the victory in just over an hour with an unreturnable serve.
"Always tough matches against Andreeva, she's so young but playing such great tennis," the 26-year-old said on the court.
"I'm super happy to get through this difficult match in straight sets."
The Belarusian had struggled with her serve in her third-round contest and said she was much happier playing in the hotter temperatures on Rod Laver Arena on Sunday.
"I'm super happy with my level today and I hope the conditions stay the same for the rest of the tournament," she added.
Neither player lost a point on their serve for the first three games but four straight forehand errors from Andreeva handed Sabalenka a break for 3-1.
The top seed never looked back from there, wrapping up the first set in 25 minutes and breaking again for 2-1 in the second on the back of a couple of double faults from Andreeva.
It was not all power from Sabalenka, who summoned up a couple of subtle drop shots as evidence of the wider repertoire she has been trying to add to her game.
Andreeva managed to put some pressure on Sabalenka's serve at 3-2 down but an ace and a drop shot helped the US Open champion see off the only three break points she would face in the contest.