The two goals move Ronaldo up to 11 for the campaign, and became the first player in Europe's top five leagues to manage at least ten goals in each of the last 15 seasons.
Leonardo Bonucci got Juventus' third goal before the halftime break, while the Portuguese was denied a hat-trick after hitting the woodwork in the second stanza.
"I think this is a good way of playing and it's important we must play with confidence".
It's a quick turnaround for Juventus as they travels to Sampdoria midweek, while Udinese host Cagliari over the weekend.
The game was over as a contest by half-time after Merih Demiral rose to head a corner towards the six-yard box, where Bonucci was on hand to nod in off the crossbar. Keeping track of the defender marking him and Udinese's backline, Ronaldo made a run forward, meeting a perfectly-placed ball from Gonzalo Higuain and striking it home.
Gian Piero Gasperini's side remain sixth after goals from Rodrigo Palacio and Andrea Poli put Bologna in command before Ruslan Malinovskiy pulled one back.
Despite a slow start to this particular Serie A season, Ronaldo appears to have found his stride once again, and is back in goal scoring form for the Old Lady.
Hellas Verona fought back from three goals down to draw 3-3 against Torino.