The 12-time champions from the Spanish capital became the first team in the Champions League era to win back-to-back titles with their 4-1 victory over Juventus at the Millennium Stadium.
Real Madrid captain Sergio Ramos grabbed hold of the Champions League trophy for the second year in a row and held it aloft as the fans still in the stadium roared.
Madrid started the competition, then known as the European Cup, with five straight titles from 1956-60. But since the 1992-93 season, when it was rebranded the Champions League, no team had been able to successfully defend its title.
Ronaldo scored two of the goals, making him the leading scorer in the competition for the fifth straight season with 12 — one more than Lionel Messi. He also became the first man to score in three finals, adding to his goals in the 2008 and 2014 finals.
It was also the second Champions League title won under coach Zinedine Zidane, the former France great who took over at his old club last season and led it to the Spanish league title last month.