Federico Bernardeschi scored a 93rd-minute winner, moments after Juve had a goal ruled out by VAR with Ronaldo at the centre of the incident.
The Portugal captain, a £99.2m signing from Real Madrid, handled the ball before colliding with Chievo goalkeeper Stefano Sorrentino in the build-up to Mario Mandzukic's goal, which referee Fabrizio Pasqua ruled out on review.
Sami Khedira had put Juventus, who have won the past seven Serie A titles, ahead from close range in the third minute, before Mariusz Stepinski headed in the equaliser.
Emanuele Giaccherini won and scored a penalty to put Chievo in front on 56 minutes, but a Mattia Bani own goal pegged them back before Bernardeschi struck late on.
Ronaldo forced several saves from 39-year-old Sorrentino, who left the match on a stretcher after his late collision with the five-time Ballon d'Or winner.
How did Ronaldo get on?
Ronaldo, 33, scored in his first game for the Old Lady - their traditional pre-season friendly against the Juventus B team.
That match was held in the small Italian town of Villar Perosa. Its population is 4,000 - but Ronaldo's appearance drew 5,000 fans.
His presence in Verona led to Chievo selling out their 39,000-seater Stadio Marc'Antonio Bentegodi, as they more than doubled their average attendance.
Speaking before the match, coach Massimiliano Allegri said he is yet to decide Ronaldo's best position in the team.
With Gonzalo Higuain on loan at AC Milan, the former Manchester United forward started up front on his own against Chievo, with Paulo Dybala in the number 10 role and Douglas Costa and Juan Cuadrado on the wings.
His first chance came in the 19th minute, when he dragged a shot wide from 20 yards. Ten minutes later he tried to volley a left-foot shot across goal from a tight angle.
Ronaldo grew into the game after the break and made his intent clear with a fierce dipping shot from distance that forced Sorrentino into action. He then directed a free header straight at the goalkeeper.
With the introduction of Mandzukic as a central striker in the 64th minute, Ronaldo moved out to the left.
He seemed more effective cutting in on his right foot, and his best chance came when he forced a diving one-handed save from Sorrentino with a curling shot.
A last-ditch tackle by Fabrizio Cacciatore deflected another Ronaldo shot onto the roof of the net, before Sorrentino saved a trademark free-kick.
How did Juve's other debutants get on?
While there were cheers for Ronaldo, there were some boos for Leonardo Bonucci, who rejoined Juve just a year after leaving for AC Milan for £35.1m.
Bonucci was at fault for Chievo's opener, failing to track Stepinski's run, but redeemed himself as his pressure at a corner led to Bani's own goal.
Former Liverpool midfielder Emre Can, meanwhile, almost scored with his first touch after coming on for the last five minutes, but his diving header was saved.
Right-back Joao Cancelo, a summer arrival from Valencia, gave away a penalty for a lunge on Giaccherini.
Ronaldo's debut in pictures
All eyes were on Ronaldo in Verona
There was a minute's silence for the victims of Tuesday's bridge collapse in Genoa
Ronaldo was involved in VAR controversy at the end of the game
Juventus eventually got the winner
