The 36-year-old has finally completed his two-year deal with his former club, who have the option of extending that by a further 12 months in 2023.
Ronaldo had previously enjoyed six years at Old Trafford during his first spell when he was signed by Sir Alex Ferguson in 2003 from Sporting Lisbon.
The Real Madrid top scorer enjoyed a fantastic relationship with Ferguson and the Scot is believed to have spoken to the forward last week to convince him to return to the Theatre of Dreams.
And, in a lengthy post expressing his happiness at returning to the Red Devils, Ronaldo finished an Instagram post by saying his decision was ‘for’ Ferguson.
“Everyone who knows me, knows about my never ending love for Manchester United. The years I spent in this club where absolutely amazing and the path we’ve made together is written in gold letters in the history of this great and amazing institution.
I can’t even start to explain my feelings right now, as I see my return to Old Trafford announced worldwide. It’s like a dream come true, after all the times that I went back to play against Man United, and even as an opponent, to have always felt such love and respect from the supporters in the stands. This is absolutely 100% the stuff that dreams are made of!
My first domestic League, my first Cup, my first call to the Portuguese National team, my first Champions League, my first Golden Boot and my first Ballon d’Or, they were all born from this special connection between me and the Red Devils. History has been written in the past and history will be written once again! You have my word!”
I’m right here!
I’m back where I belong!
Let’s make it happen once again!
PS – Sir Alex, this one is for you…