Torino had not won the Turin derby, known as the Derby Della Mole, in 12 attempts before Saturday’s showdown at the Allianz Stadium, having recorded one win against Juventus in more than 25 years.
Arriving with the worst defense in the division, they began the evening as huge underdogs and watched as Ronaldo proudly received a shirt from Juve president Andrea Agnelli on the pitch, branded to commemorate the 750th career goal he scored in the 3-0 Champions League win against Dynamo Kiev on Wednesday.
There were no such home comforts for Juventus against their third-from-bottom opponents, going a goal behind after Nicolas Nkoulou pounced on slack marking at a free-kick with just nine minutes gone.
Ronaldo, who also received the official Most Valuable Player award for the month from Serie A before kick-off, was evidently brimming with confidence as he inaccurately attempted a shot on goal straight from kick-off.
The Portugal captain was otherwise anonymous by his standards as Juventus took 43 minutes to have a shot on goal, strike partner Paulo Dybala shooting tamely at Salvatore Sirigu.
Juventus thought they had equalised in the second half when Juan Cuadrado found the net, but fans were left with a familiar sense of outrage after a VAR check adjudged Leonardo Bonucci to have interfered with play from an offside position.
Torino almost held on before American star Weston McKennie rescued Juve with a late equaliser, scoring his first Serie A goal for the club and becoming the first American to score for them in the league as the midfielder launched their comeback.
Captain Bonucci then made up for his earlier frustration by netting an 89th minute winner as his side scraped to victory with their latest stuttering display.
The win did little to ease uncertainty among fans over the tactics employed by rookie boss Andrea Pirlo, as the reigning champions finished the evening three points behind leaders AC Milan, who have a game in hand.