The Portuguese superstar recently celebrated his 34th birthday.
He is showing no sign of slowing down, with a productive debut campaign having been taken in at the Allianz Stadium.
His best efforts have not been enough to help Juve past the quarter-final stage of the Champions League, but a Serie A title success will soon be wrapped up.
Ancelotti believes there will be many more years of trophy-chasing for Ronaldo, with the five-time Ballon d’Or winner being backed to prolong his career and help mould that of exciting teenage team-mate Moise Kean.
On the two high-profile performers on Juve’s books, Ancelotti said: “I was impressed and surprised by Kean.
“His beginning of the year was amazing and there's been careful management of the player, on and off the field.
“He has the good fortune of training with a phenomenon of the calibre of Cristiano.
“He'll play up to 40 years old because he not only has a great physique but he has the intelligence, the strength and the determination to improve every day.”
Kean has impressed this season when called upon by Juve.
He has helped to cover the absence of Ronaldo at times, recording goals when his iconic colleague has either been injured or rested.
The 19-year-old forward will be hoping that there are more outings alongside the Portuguese to come.
Ronaldo penned a contract through to 2022 when linking up with Juventus.
He has previously suggested that he will look to extend his playing days for as long as possible, saying back in 2017 during his time at Real Madrid: “When I renewed my contract I said I'd still be playing when I'm 41 - it was meant half-jokingly and half-seriously.
“If I feel good, without any injuries and I am still motivated, I'll play until I'm 35, 41 or 45. I don't know.
“I can't see myself going into coaching. That looks unlikely. But I don't know what will happen in the future.
“At the moment, I'm only focusing on my playing career.”