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.
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.
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.
