The normally aggressive Australian Open champion, who could potentially replace Iga Swiatek (22) at the top of the world rankings by lifting the Venus Rosewater Dish, bagged the first set with a late break playing some delightfully delicate shots at the net.
Alexandrova had eased past her Belarusian opponent in their previous two meetings but a repeat was never on the cards under bright sunshine on Court One as Sabalenka pounced early in the second set for a 4-0 lead.
Serving with power and precision, the 2021 semi-finalist tightened her grip on the match with a solid hold and closed out the contest when fast-fading 21st seed Alexandrova sent a shot long at the baseline.
Sabalenka, who has dropped only one set in the tournament so far, will face American 25th seed Madison Keys (28) in the last eight.