The Belarusian has yet to drop a set in Melbourne and was again impressive in beating Benesova 6-2 6-2 in 77 minutes.
Azarenka came out firing and a break in the opening game set the tone, the third seed's greater power from the baseline proving too much for her Czech opponent.
Another break handed her a 4-1 lead and she duly served out the set.
Benesova required a strong start to the second set to have any chance of hitting back, but instead Azarenka broke once more.
She then established a 3-0 lead when a dispirited Benesova double-faulted.
From there on in it was a stroll in the Melbourne sunshine for Azarenka as she eased to a last-eight meeting with Agnieszka Radwanska.