Ronaldo made a blockbuster move to Juventus from Real Madrid, where he spent nine seasons, in the summer.
But the Portuguese star has struggled to get going in front of goal for his new club.
However, after three scoreless matches for the Serie A champions, Ronaldo finally broke his duck in the 50th minute.
Sassuolo failed to deal with a corner into their box with one of their defenders heading the ball onto the post.
And from the rebound, Ronaldo reacted quickest and flicked the ball in the net.
Ronaldo then sprinted away and produced his trademark celebration.
Then in the 64th minute, Ronaldo got his and Juventus’ second of the match.
Juventus hit Sassuolo on the counter-attack with Emre Can leading the breakaway.
The former Liverpool midfielder then laid the ball off to Ronaldo, who took a touch with his right foot and rifled a left-footed shot into the bottom corner.
Ahead of the game, Ronaldo’s manager Massimiliano Allegri said it was just a matter of time before he scored.
“Cristiano has been training well. I think tomorrow could be his day,” he said.
“I believe that Cristiano deserves to win the FIFA World Player award, even if Luka Modric has had a phenomenal year as well.”