The Portugal forward had been self-isolating since testing positive for the virus while away on international duty in early October.
Ronaldo has not played for Juve since a 2-2 draw against Roma at the end of September, and this week missed a reunion with Barcelona adversary Lionel Messi in the UEFA Champions League.
A statement from Juventus read: "Cristiano Ronaldo carried out the check with a diagnostic test (swab) for COVID-19.
"The examination gave a negative result. The player is therefore cured after 19 days and is no longer subjected to home isolation."
But as Ronaldo recovered, other cases were announced in the Italian top flight.
In Bergamo, Atalanta coach Gian Piero Gasperini's pre-match press conference before this weekend's game at Crotone was cancelled after a positive case among the coaching staff.
Crotone also confirmed that its midfielder Salvatore Molina had "slight symptoms" and is isolating at home.
Sassuolo, which travels to Napoli, has three new cases, one a player, while Parma, which plays at Inter Milan, revealed two players had become infected for a second time.
Lazio is awaiting tests results after players including star striker Ciro Immobile and Luis Alberto missed the UEFA Champions League draw at Club Brugge as a precautionary measure.
Coach Simone Inzaghi's press conference before Monday's (AEDT) game against Torino has been cancelled with half the squad reported to be self-isolating.
The Rome club is scheduled to travel to Torino on Monday (AEDT) before hosting Juventus the next weekend.
AC Milan goalkeeper Gianluigi Donnarumma and striker Jens-Petter Hauge tested positive earlier this week.
Serie A is applying UEFA rules whereby a match can take place as long as a side has 13 healthy players, including a goalkeeper.