Ferdinand played a role in United sealing Ronaldo’s return, making contact with the 36-year-old on Thursday after hearing of City’s interest.
He added: “I was talking to him and texting him about it. Our friendship goes back many years from when we played together. We’ve stayed close ever since then.
“The situation came about on Thursday night and materialised on Friday, so really, really interesting but it happened in the end.
“The moment myself and a few people at the club heard that he could be going to Manchester City, you could never see him wearing a sky blue kit. It just couldn’t happen.
“I reiterated on my YouTube channel that the Manchester United hierarchy acted well on every step to get this deal done.”