Ronaldo and his family landed in Turin Airport just after 10.20pm local time, according to media reports in Italy.
The five-time Ballon d’Or winner arrived by private jet from the Portuguese island of Madeira and will spend two weeks in quarantine.
The 35-year-old played Juventus’s last Serie A game, a 2-0 win over Inter Milan behind closed doors at the Allianz Stadium on March 8, before the Italian football season was suspended amid the COVID-19 pandemic which has killed over 29,000 people in the country.
Ronaldo returned to Madeira after the Inter Milan match to be close to his mother Dolores who had suffered a stroke.
Juventus have recalled their 10 overseas players as Serie A clubs were given the green light to return to individual training on Monday.
The Italian interior ministry’s go-ahead for players to return to club training facilities two weeks ahead of schedule has offered fans hope that the 2019-20 season might yet be salvaged.
Juventus are leading Serie A, one point ahead of Lazio, as they target a ninth consecutive Scudetto.
The club has not yet given an official date for a return to training.
Juventus began carrying out tests on their players at the club’s medical centre in Turin on Monday.
The first to arrive were Federico Bernardeschi, Juan Cuadrado, Carlo Pinsoglio, Leonardo Bonucci and Aaron Ramsey, all wearing face masks.
Juventus are also waiting the return to Turin of Dutch centre-back Matthijs de Ligt and midfielder Blaise Matuidi, who returned to France after recovering from the virus.
Gonzalo Higuain remains in Argentina where he returned to be with his sick mother.