It took the five-time Ballon d'Or victor 320 minutes and 27 shots to finally get off the mark for his new club, and it is unlikely he will ever score a more simple goal in his illustrious career the his first for Juve.
The hosts went agonsingly close in the 38th minute when Sassuolo shot-stopper Andrea Consigli pulled off a stunning save to stop Pol Lirola from deflecting the ball into his own net.
He's off the mark!
However, Juve held on to claim three points and their fourth win of the season.
However, relief came for the Portuguese star and millions for his fans across the world in the 50th when Gian Marco Ferrari's wayward defensive header hit the upright and Ronaldo was quickest to react on the rebound from a yard.
Ronaldo has won the Champions League five times, including each of the last three seasons with Madrid, and one of Juve's prime reasons for signing him was so they could win the competition for the first time since 1996.
The five-time Ballon d'Or victor was denied a hat trick by a fine save from Sassuolo goalkeeper Andrea Consigli, while he also mishit a clear opportunity late on.
Embroiled in a heated discussion with Sassuolo's Federico Di Francesco, the Brazilian winger proceeded to spit into the mouth of Di Francesco before walking away.
Juventus, seeking a record-extending eighth successive Serie A title, are the only team still with a ideal record.
The clash ended on a sour note as Douglas Costa was shown a straight a red for an incident off the bal.