It means the Portuguese forward is the first player to reach a half-century of goals in Serie A, La Liga and the English Premier League.
His 30 league goals in 30 matches this campaign puts the 35-year-old alongside Ciro Immobile, who scored late on for Lazio, as Serie A's leading goalscorers.
Juventus had been without a win in three matches before Monday's game, but the victory saw the Bianconeri move eight points clear of second-placed Inter Milan with four games remaining and close in on a ninth successive league title.
Ronaldo downplayed his landmark goal at the final whistle.
"Records are always important, but what matters is the team," he said.
"We are doing phenomenal work and the important thing is to end like this, to win -- the records come from a natural process, but what matters is to bring home the league title."
Following a goalless first half, Ronaldo broke the deadlock from the penalty spot after Bastos was judged to have handled the ball in the box.
His second came minutes later courtesy of a long run from Paulo Dybala, who won possession in his own half and selflessly fed Ronaldo in front of goal.
Immobile pulled one back for the visiting side with eight minutes to play after he was brought down by Leonardo Bonucci in the Juventus box and converted the resulting penalty, but the defeat sees Lazio remain fourth.
Juventus, meanwhile, need at least four points to secure the title.
"All the games are difficult now, and in the space of six days, we play three games," said manager Maurizio Sarri.
"So we must stay focused and think about securing the missing points.
"Cristiano is an impressive player because he has the extraordinary ability to complete a quick recovery between games.
"Not only physically, but, above all, mentally -- he is a champion with his feet, but also with his head."
Juventus next faces Udinese on Thursday.