Carlos Tevez, Arturo Vidal and Fernando Llorente all netted before Luca Rossettini scored a late consolation for the struggling Sardinians
Back-to-back draws against Fiorentina and Sampdoria meant Massimiliano Allegri's team travelled to Sardinia with a slender one-point advantage over nearest challengers Roma.
Carlos Tevez scored from close range to hand the defending champions an ideal start and Arturo Vidal struck a sumptuous second to make it 2-0 after 15 minutes.
Fernando Llorente added a third early in the second half and, although Luca Rossettini pulled a goal back, Zdenek Zeman's strugglers remain winless in the league since late October and in the bottom three.
By contrast, Juventus are now unbeaten over 10 matches in all competitions.
Cagliari, without a home win in the league all season, were boosted by the return of Victor Ibarbo in attack.
Angelo Ogbonna started at centre-back for Juventus in place of the suspended Leonardo Bonucci, while fellow defender Giorgio Chiellini came back from a ban of his own.
Allegri started without Paul Pogba, the influential midfielder rested as a further yellow card would have ruled him out of the Monday night's Supercoppa Italiana clash with Napoli in Qatar, but his Juventus team immediately tore into Cagliari and were rewarded with a third-minute lead.
Alessio Cragno had already plunged to make a fine save from Llorente's header, but, when Chiellini bundled goalwards from another right-wing cross, the Cagliari goalkeeper could only touch towards Tevez for a simple finish.
Juventus looked to further exploit Cagliari's unease under crosses, but Gianluigi Buffon was called into action for the first time to keep out Albin Ekdal's header.
That chance briefly roused Cagliari, but they fell further behind when Patrice Evra's centre was half-cleared and Vidal curled home a magnificent side-footed finish from outside the box.
Allegri's men were now able to control the game at a comfortable pace, although Cagliari's Danilo Avelar was allowed to advance towards goal and flash a shot past Buffon's near post three minutes from half-time.
Ekdal shot wide when given room to try his luck from 25 yards after the break before Juventus put the result beyond doubt five minutes after the restart.
Andrea Pirlo lifted a perfectly weighted pass into Llorente’s path and the Spain striker spun Luca Ceppitelli before scuffing a shot that squirmed past Cragno.
Marco Capuano volleyed over unmarked from a corner as Cagliari looked to respond and they grasped a lifeline in the 65th minute when Rossettini rose to power home at the back post.
But Juventus' superiority was never truly under threat as the lively Roberto Pereyra twice went close to adding gloss to the scoreline during the closing stages.
Avelar might have set up a grandstand finish, but lashed wide from close range in the 87th minute after Stephan Lichtsteiner blocked his initial header.