Four-time major champion Sinner, who extended his winning streak at hard-court Grand Slam tournaments to 25 matches, took eight of his 17 break opportunities.
Going into the match, Bublik had won all 55 of his service games in the tournament.
Bublik spoke about the importance of holding serve early in the match but, having completed victory over American hopeful Tommy Paul shortly after 1:15am local time on Sunday morning, he instantly looked out of sorts.
Losing serve in the first game – down to sloppy groundstrokes and a double fault on break point – set the tone.
After Sinner seized control, his athleticism soaked up the drop-shots and underarm serves thrown his way by the unpredictable Bublik.
There was also no let-up in the ferocity of the top seed’s groundstrokes.
Bublik could not handle the pace being thrown at him, before his double fault on Sinner’s first match point summed up a difficult evening.
In the face of such adversity, Bublik still managed to play with a smile on his face and shared a joke at the net with Sinner following his heavy defeat.
“You’re so good, this is insane. I’m not bad,” the 28-year-old said.
Perhaps the only consolation for Bublik was avoiding being at the wrong end of the fastest beating of the tournament.
Surviving three break points to hold serve for 4-1 in the final set helped him slightly prolong the match, taking it past the one hour and 20 minutes which Czech 21st seed Tomas Machac took to beat Italy’s Luca Nardi in the first round.
Sinner goes on to face 10th seed Lorenzo Musetti in an all-Italian quarter-final.