Ronaldo's conduct has come under increasing scrutiny of late, with the player facing potential disciplinary action for a goal celebration in his side’s 2-1 loss to Barcelona on Sunday.
Varane, however, told La Voix du Nord: "This is a superstar. But also a very professional guy; always listen to your body to be on top physically.
"This is an outstanding competitor, always 200 per cent, an example to follow in everyday life."
Meanwhile, Varane expressed a desire to make his mark at the Bernabeau amid talk linking him with a move to Premier League leaders Chelsea
"I feel progress this season, including going through difficult times. This is where we learn the most.
"I turned a corner mentally. I can progress in a lot of areas, but what I would like is to impose my mark in the team.
"It's a goal that I try to move forward. When you are at Real, it's a challenge every day. I'm like that, I need these high goals to keep moving forward."
The 21-year-old has made 34 appearances for Real this season after an indifferent 2013/14.