The assistant coach feels that los Blancos offer the prolific attacker the perfect conditions to flourish and has defended Jose Mourinho's decision to drop Pepe
Paris Saint-Germain are believed to be monitoring the Portugal international's situation at Madrid while Manchester United have long been linked with a move for their former star, and Jose Mourinho's imminent exit from the club has added fuel to the rumours.
However, Ronaldo - who netted his 200th goal for Real Madrid on Wednesday as they battered Champions League quarter-finalists Malaga 6-2 - is already at the club which suits him best, according to Mourinho's assistant.
"The coach has already answered questions about Ronaldo's future. Here is the ideal place for him and for Real Madrid it is great to have him," Karanka said at a press conference.
"The kind of player he is and the club where he is - Real Madrid - are good for each other. He will keep getting better."
Karanka then went on to discuss Mourinho's decision to drop Pepe in favour of Raphael Varane, defending the boss from criticism over the issue.
"The performances Varane has been putting in are being seen by everyone. You were all saying that Pepe was not a Real Madrid player before and now you are all defending him.
"I know the type of player that Pepe is and I still think the same of him. Match-day squads and line-ups are made based on players’ performances on the field and always for the team to win."