Juventus' points haul of 53 at the halfway point of a 20-team Serie A season is a new record.
Ronaldo got Juve off the mark after just two minutes, as he cut in from the left and found the bottom-right corner.
Fabio Quagliarella equalised with a penalty just after the half-hour mark, but Ronaldo netted a spot-kick of his own in the second half.
Juve were saved by VAR towards the end as Riccardo Saponara had a goal disallowed, leaving them 12 points clear of second-placed Napoli for at least a few hours.
Massimiliano Allegri's men are still unbeaten at the season's halfway mark, having dropped just four points all season.