Ronaldo leaves Madrid after a trophy-rich spell which saw him lifting 16 titles, including four UEFA Champions Leagues - including the last three- and two league titles as well as three FIFA Club World Cups titles.
The transfer fee was not disclosed but Spanish media said Ronaldo had signed a four-year deal and had cost Juventus 105 million euros ($123.24 million).
"These years at Real Madrid and in this city of Madrid have been possibly the happiest of my life", he said.
"I feel that way and I ask everyone, and especially our followers, to please understand me". He won the European Championship two years ago with Portugal (a feat his former coach Zidane labeled the hardest competition to win in soccer), and he has won several Premier League titles during his brilliant stint with Manchester United, plus several more La Liga titles while manhandling the competition with Real Madrid. And that's exactly what Ronaldo, the player and the brand, will bring to the Italian club.
The Portugal global scored two goals against Juventus in Real's 4-1 win in the 2017 Champions League final and earlier this season struck a jaw-dropping bicycle kick against the Italians in a 3-0 win in a quarter-final first-leg game in Turin which prompted Juve supporters to give him a standing ovation.
"I do not want to denigrate the Belgium team of the time, there were very good players, but at that time, it was France".
The winger was converted into an out-and-out striker, scoring an incredible 451 goals for Los Blancos in just 438 matches, smashing the club's previous scoring record of 323 held by Raul.
"It is true that [Zidane] is special, but Madrid makes everyone dream".
If Ronaldo does end up leaving the club, Real Madrid will have a massive hole to fill in attack, to go with the financial means that have defined the club for years.
Serie A will be the third of Europe's four biggest leagues that Ronaldo has graced, and his move shows that none of his drive and ambition have decreased in the latter stages of his career.