He signed a 4-year contract with the club and will be paid an approximate amount of 30 million Euros per season. 

This is what Ronaldo said in his official statement post the transfer. 

These years in Real Madrid, and in this city of Madrid, have been possibly the happiest of my life. I believe that the time has come to open a new stage in my life and that is why I have asked the club to accept transferring me. I feel that way and I ask everyone, and especially our followers, to please understand me.  

You can read the complete letter, here.

The transfer comes for the Portuguese star after 9 years of playing for Real Madrid when he saw great heights as one of the club’s most prominent faces. 

According to India Today, he was allegedly unhappy with president Florentino Perez had dropped a hint about the exit after the Champions League final in Kiev this year. 

In an official statement, Real Madrid said:

Real Madrid C.F. communicates that, in response to the will and request expressed by the player Cristiano Ronaldo, he has agreed to transfer to Juventus FC. 

While further adding:

Today, Real Madrid wants to express its gratitude to a player who has proved to be the best in the world and who has marked one of the brightest times in the history of our club and world football. Beyond the conquered titles, the trophies achieved and the triumphs achieved in the playing fields during these 9 years, Cristiano Ronaldo has been an example of dedication, work, responsibility, talent and improvement.

Lastly they added, 

For Real Madrid Cristiano Ronaldo will always be one of his great symbols and a unique reference for the next generations. Real Madrid will always be your home.