Last season, Ronaldo helped Real Madrid win the Champions League and their first La Liga title since 2012.
Ronaldo added the 2017 Ballon d'Or to those he won in 2008, 2013, 2014 and 2016, and Messi is the only other recipient of the award since 2009.
"This is something I look forward to every year," he said, after receiving the award on the Eiffel Tower in Paris.
"Thanks to my Real Madrid team-mates. And I want to thank the rest of the people who helped me reach this level."
The 2016-17 campaign was a stellar season for the former Manchester United player.
After helping Portugal win Euro 2016, he scored 42 goals for Real in all competitions as they won their 33rd La Liga title and 12th European Cup.
He scored twice in a 4-1 Champions League final win over Juventus and netted 25 times in 29 league games as Los Blancos finished three points ahead of Barcelona.
What is the Ballon d'Or?
The Ballon d'Or is voted for by 173 journalists from around the world.
It has been awarded by France Football every year since 1956, but for six years it became the Fifa Ballon d'Or in association with world football's governing body and was awarded to the world's best player.
However, Fifa ended its association with the award in September 2016.
At Fifa's awards in October, Ronaldo was named the world's best male player and also named in the Fifpro World XI.
How did Premier League players do?
Chelsea midfielder N'Golo Kante was the highest-placed Premier League player, finishing eighth. The France international won his second successive top-flight title last season and was named both the PFA and Football Writers' player of the year.
Tottenham striker Harry Kane, the only Englishman on the shortlist, finished 10th, Manchester City midfielder Kevin de Bruyne was 14th and Chelsea playmaker Eden Hazard was 19th.
Liverpool forward Sadio Mane was 23rd while team-mate and playmaker Philippe Coutinho was 29th.
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