Juventus welcomed back Matthijs De Ligt from a shoulder injury, as Leonardo Bonucci and Giorgio Chiellini missed out due to injury, while Cagliari were out Diego Godin who tested positive for Coronavirus.
The hosts had the ball in the net in the first ten minutes through Federico Bernardeschi, but it was brought back after Alvaro Morata who set up the goal strayed offside.
Juventus did have more chances following the midway stage when Morata headed over the top from a corner-kick, while Dejan Kulusevski curled wide of the bottom-corner later on.
The Bianconeri made their dominance count seven minutes before halftime with Ronaldo feeding off a pull back from Morata on the edge of the area to bend into the far post.
Ronaldo secured a second on 42 minutes after landing onto a flick on from Merih Demiral following a corner by Juan Cuadrado before firing into an empty net from an unmarked position.
Cagliari turned to the bench after halftime and called on Riccardo Sottil, who entered in place of Alessandro Tripaldelli in an offensive move.
The Rossoblu weren't out of the woods after 52 minutes with Demiral sending a well-placed corner from Cuadrado onto the crossbar.
Ronaldo had a chance to complete a hat-trick three minutes later after meeting a ball from Kulusevski but instead of shooting, dummied to Bernardeschi who went wide.
Juventus continued to hold momentum later on, as the visitors struggled to cause the all-conquering Italian side any issues from all angles.
At the end, the Old Lady sustained the closing minutes to revive their pursuit for a tenth straight league title.
