The Portugal international has claimed four Ballons d'Or in his career, three of which have come during his time at Madrid.
After winning his second Liga title since arriving in 2009, he can lift his third Champions League crown with the club and fourth overall, having won it with United, when they take on Juventus in next week's final.
The 32-year-old is widely regarded as one of the best players the game has ever seen, and ex-Madrid and United forward Owen feels Sir Alex Ferguson had a big role in his development during their six years together at Old Trafford.
"He was absolutely off the scale in how he was performing at United,” Owen said. “So I don’t think Real Madrid can take the credit at all because United and Sir Alex Ferguson groomed him in that way and he continued to progress at Real.
“Ronaldo had a couple of out-of-this-world seasons at United at the end and has not stopped improving. He is a one-off, he really is. Ronaldo and Messi have taken football to a new level for so long as well, consistently being top of the tree.
“People don’t realise that it’s so hard to become what Cristiano has become because if you painted the perfect picture of a football player it’s just Ronaldo. He’s the perfect height, he’s not too tall, a perfect height and shape. He’s quick, two-footed, brilliant in the air, durable and he scores goals for fun.
“If you typed all of those attributes into a computer you couldn’t come up with a more perfect player than Ronaldo. He’s got the lot. And added to that what he’s got between his ears as well in terms of the confidence, the arrogance and self-belief to be the best, it’s hard to see anyone coming close to him in the future."
Owen also pointed out the Euro 2016 winner's commendable work rate and believes his arrogance has helped him become a star.
“Don’t dismiss the way he lives his life either and the dedication he has to becoming better every day. Not everyone is like that. So there are lots of different elements to him being the best and he is certainly that.
“I find goalkeepers and scorers are pretty unique in the way they think. And, unfortunately, you have to be an arrogant so-and-so to be a centre-forward who constantly scores goals.
“You must think and behave in a certain way and have that much self-belief and selfishness – it’s a unique thing to have. People criticise him if he doesn’t score, doesn’t look happy or isn’t playing well. But if he wasn’t like that and you take away that mentality then he won’t score all the time.
“It’s great being the best, but after that you are petrified of someone taking your mantle. And that’s why his rivalry with Messi feeds off all of that. And in that battle he comes out on top for me simply because there are less question marks about him.
"He is pure perfection.”