With Juventus down 1-0 to Torino late in the game, Ronaldo rose up from six yards out to nod Leonardo Spinazzola's cross past Salvatore Sirigu.
The 84th-minute equaliser salvaged a 1-1 draw for Juventus in the Turin derby, with Ronaldo now having scored seven goals in his last nine Serie A appearances.
The Portuguese has now reached 101 headed club goals in his career and he has been especially prolific in the air of late, with seven of his last 10 goals in all competitions coming from headers.
Ronaldo's goal also prevented Torino from winning away at Juventus for the first time since 1995, with Juve winning nine and drawing four of the 13 games since then.
Torino could have drawn level on points with fourth-place Atalanta had they held on for a win, but Walter Mazzarri's side are still in the midst of a record-setting campaign.
The Granata are on 57 points so far in 2018-19, equalling their club record haul in the three-point era set in the 2013-14 season.
Juve's ability to come from behind is a major reason they so easily won another Scudetto, with Massimiliano Allegri's side now having gained 21 points from trailing situations this season, the most in Serie A.
Massimiliano Allegri's men will close out the season with games against Atalanta and Sampdoria.