Sasa Lukic had fired Torino ahead after 17 minutes in a match brought forward a day to avoid clashing with Saturday's 70th anniversary of the air disaster that wiped out the all-conquering 'Grande Torino' team of the 1940s, AFP reported.
But Ronaldo headed in for 1-1 after 84 minutes to leave Torino in sixth place, two points off the Champions League berths with three games left to play.
Juventus has already sealed the Serie A title for the eighth season in a row, but Torino still has all to play for as it targets a first-ever qualification for elite European competition.
"This draw burns, we could have scored a second goal and brought the win home," said Torino coach Walter Mazzarri.
"The only time we let down our guard the phenomenon that is Ronaldo punished us."
Torino has not won at Juventus since 1995 while its only win since then against its city rival was at home in April 2015.
Ronaldo hits 601st
It was Ronaldo's 21st league goal this season and moves him two behind Sampdoria's Fabio Quagliarella, who leads the Serie A scoring charts.
The Portuguese superstar brought his tally of career club goals to 601, edging ahead of his Argentina rival Lionel Messi, who has 600.
"We're lucky to play with Cristiano and live in this age of two star players," said Juventus captain Giorgio Chiellini.
"They're somewhat comparable to (Roger) Federer and (Rafael) Nadal. They are both out of this world, one seems stronger one day and then the other replies."
For Juventus it was a second consecutive stalemate after last weekend's 1-1 draw against Inter Milan.
"Clearly once you've won the league the foot comes off the gas a little bit and it becomes difficult to find the motivation," said coach Massimiliano Allegri.
"But compared to the San Siro we started better and if we hadn't conceded that goal in the first half it might have been a different game."
Juventus is nevertheless 19 points ahead of second-placed Napoli, which hosts Cagliari today.
Torino stays sixth, one point behind Roma, and two adrift of fourth-placed Atalanta.
Although Juventus has nothing left to play for it will have a role in who qualifies for next seasons Champions League as it plays Roma and Atalanta in their next two games.