The 33-year-old's move to the Italian giants was confirmed on July 10, ending his illustrious nine-year stint at the Bernabeu.
Ronaldo passed his medical on Monday and was unveiled by the club later in the day as the move - believed to be in the region of £99m - was completed.
"[Juventus] have won domestic cups and Serie A titles, and they were in the final of the Champions League, so I am so proud to be here, I am so proud that they were interested in me," Ronaldo told reporters at Monday's press conference.
"I hope I can give the best response on the field during matches, that's what I can do. I hope I can take them to an even higher level."
The Portugal international and Euro 2016 winner scored a club-record 450 goals in 438 appearances for Real, helping the club to 15 trophies including four Champions League titles.