Fernando Llorente's second-minute strike set the hosts on their way to a sixth consecutive home win, with Andrea Pirlo's sublime free-kick and a stunning Paul Pogba volley wrapping up the points after the break.
Angelo Ogbonna's late sending off took some shine off Juve's fourth league win on the bounce, but the defending champions now have the summit in their sights after moving into second.
For the visitors, the result ended their five-match winning run in all competitions as they failed to capitalise on Roma's draw with Sassuolo.
Both teams had won their three previous games but it was Antonio Conte's men who made the decisive start.
Pogba's bouncing shot was tipped behind by Pepe Reina and from the short corner, Arturo Vidal's shot was flicked on to Llorente by Carlos Tevez and the Spaniard made no mistake from close range after only two minutes.
It would have been two but for a tremendous save by Reina. Pirlo's deep cross was headed across by Pogba towards Leonardo Bonucci six yards out but his point-blank header was somehow saved by the goalkeeper and Napoli scrambled clear.
More than 20 minutes passed before Napoli registered a shot on target but Lorenzo Insigne's effort on the turn was easy for Gianluigi Buffon.
Insigne almost provided an equaliser after 32 minutes when he found space in the area but his left-foot drive whistled past the post, while Reina had to be alert to thwart Llorente's near-post header.
The back and forth contest almost swung in favour of Benitez’s team just before the break and again it was Insigne who provided the danger with a dipping long-range strike that landed on the roof of the net.
Pirlo added the second with typical finesse, the midfielder's inch-perfect free-kick flying into the top corner from 25 yards.
Ogbonna's obstruction of Dries Mertens saw him dismissed for a second booking with seven minutes left, but Juventus were home and dry by then.
