"After dating for five years, my relationship with Irina Shayk has come to an end," Ronaldo said in a written statement sent exclusively to The Associated Press. "We believed it would be best for both of us to take this step now."
Ronaldo said he was making the statement to end speculation about their relationship, and to end recent rumours about his private life. He did not specify the rumours, but media in Portugal have reported that Shayk fell out with members of Ronaldo's family, and that he was seeing another woman.
"I wish Irina the greatest happiness," Ronaldo said.
He gave no further details in the brief statement.
The couple, both 29, has had huge international success, and their relationship has featured in newspapers and magazines worldwide. They were not believed to be living together, as Ronaldo was based in the Spanish capital while Shayk travelled extensively.
Ronaldo recently picked up the Ballon d'Or after being voted the world's best player, but Shayk did not accompany him to the ceremony in Zurich. Her absence triggered rumours that their relationship was over. The couple remained silent despite days of intense media speculation.
Ronaldo retained football's highest individual honour after scoring 61 goals last year. His record tally of 17 in a Champions League season helped Madrid win an unprecedented 10th European Cup title.
Born in the Portuguese island of Madeira, Ronaldo played as a teenager for Sporting Lisbon before moving to Manchester United in 2003. He transferred to Real Madrid in 2009, building his reputation and his wealth through endorsements and sponsorships. He has millions of followers on social media.
Ronaldo has a 4-year-old son, called Cristiano Junior, but he has never disclosed the mother's identity.
Shayk won international fame as a Sports Illustrated swimsuit model, and a lingerie model. She made her acting debut last year opposite Dwayne "The Rock" Johnson in the film "Hercules."