The Bianconeri showed no hangover from their surprise midweek Champions League loss away to Swiss club Young Boys, rallying to extend their lead over Napoli, who play on Sunday, to 11 points.
Ronaldo made the breakthrough from the spot during the second half after Torino substitute goalkeeper Salvador Ichazo had tripped Mario Mandzukic.
The Croatian striker saw a goal disallowed for offside after a Video Assistant Review, but Massimiliano Allegri’s men went on to close out a hard-earned three points.
An early corner saw Torino goalkeeper Salvatore Sirigu clattered by Emre Can, which left the Italian needing treatment for a lower back problem.
Sirigu was soon thrown into action again when getting down to save a dipping volley from Ronaldo in the 15th minute, and again needed treatment before being able to carry on.
The goalkeeper, though, was clearly struggling and not able to take goal-kicks.
That meant Torino boss Walter Mazzarri was forced into the substitution after just 21 minutes, Ichazo coming on for a first Serie A appearance since January 2016.
Torino opened Juve up after 32 minutes when goalkeeper Mattia Perin palmed away a knockdown at the back post from Andrea Belotti.
Juve threatened again just before half-time when defender Giorgio Chiellini sent a flick from a corner goalwards, which Ichazo saved.
Torino – having lost just once in their last 10 Serie A games – had a positive opening to the second half as Armando Izzo headed over from a free-kick and Belotti’s deflected effort went over.
Juve, though, remained a threat, with Blaise Matuidi almost getting on the end of a cross from full-back Alex Sandro.
In the 68th minute, Juventus were awarded a penalty when Ichazo raced out to go through the back of Mandzukic as he darted towards the near post onto a stray backpass.
Ronaldo made no mistake from the spot, beating Ichazo with a low shot into the corner which the keeper got a hand to – and was then barged by the Portugal international as he celebrated, which resulted in a caution.
Juve thought they had doubled their lead after 73 minutes when Mandzukic crashed the ball in at the far post after a free-kick had been glanced on by Ronaldo.
But the VAR ruled Ronaldo had been marginally offside – much to the forward’s disbelief.
The outcome of the decision, however, did not in the end have a major impact as Juventus dominated possession during the closing stages, with Ronaldo seeing a chance for a late second blocked.