The Real Madrid superstar has signed a multi-year agreement with the US sports giant, reportedly worth around €24m ($27m) per year.
“I have an excellent relationship with this brand, I have great friends here and we work as a family. This is my brand,” Ronaldo said.
Nike said: “He transcends the world of football, as the most famous athlete in the world and the most popular on social networks.”
The statement also noted Ronaldo’s “extensive feedback and insights” in helping to design Nike products such as his Mercurial Superfly boots.
“His commitment to fitness has also informed Nike’s training products, while his style is regularly on display in Nike Sportswear,” Nike added.
Neil Hopkins, director at M&C Saatchi Sport & Entertainment, said the deal “underlines how valuable he is to the brand as they trade blows with Adidas and their star performer Lionel Messi”.
Hopkins added: “If, as has been reported, this is a ‘deal for life’ from Nike, then Ronaldo will be the first non-NBA star to receive such a package after Michael Jordan and LeBron James.
“What is interesting though is that the Nike deal will sit adjacent to the commercial activities that Ronaldo undertakes under his own highly successful CR7 brand.
“That range now stretches from underwear, through shirts and shoes to fragrances, demonstrating what a commercial phenomenon Ronaldo has become beyond the football sphere.”
Gavin Peters, director of partnerships at Pitch, commented on how Adidas' and Nike's approach to marketing their brand ambassadors differs.
"Adidas tends to focus more on the lifestyle and attitude around football, and using that to appeal to a younger audience, especially on social," said Peters. "Nike’s content on the other hand tends to be more around high-performance – it’s about aspiring to be the best you can be."
He also pointed out that both brands are now showing a "true understanding of their athlete’s personalities, and the ability to bring them into the process where it really works in a credible way".
The Portuguese sportsman's commercial appeal is also, to an extent, playing into the hands of Nike’s rival Adidas, which has a kit deal with Real Madrid.
Around 40% of the club’s shirt sales can be attributed to Ronaldo and his popularity is helping the Spanish club expand into new regions such as Asia.