Ronaldo, 32, earlier this month won a fifth Ballon d'Or to match the record of Argentine rival Lionel Messi.
The decorated Portugal captain believes he is the best footballer in history, with Ramos saying he certainly belongs amongst the greats.
"Our number seven is a striker like we have never seen before," Ramos told Telefoot.
"He is already a legend and will be recognised as one of the best players in the history of football.
"Cristiano Ronaldo has a very important role in the team and everyone respects it," added the Spanish defender.
Ronaldo has scored 16 times in 21 games in all competitions for Real this season, taking his tally for the European champions to a staggering 422 goals.