Massimiliano Allegri's side, who failed at the first attempt with a fell behind after a Nikola Milenkovic opener.
Alex Sandro equalised with a brilliant flicked header in the 37th minute. Victory was sealed after the break when German Pezzella diverted Ronaldo's cross into his own net.
"I'm really happy that I have won the Italian title in my first season. Of course, it did not go well in the Champions League, but there is next year," says Ronaldo.
Juventus' 35th league title means the Portuguese forward, who signed from Real Madrid for £99.2m last summer, has become the first player to win domestic titles in England, Spain and Italy, writes BBC football.