Ronaldo previously won the UEFA award in 2013-2014 and 2015-2016.
Cristiano Ronaldo has won his third UEFA men's player of the year award in four seasons, beating Lionel Messi and Gianluigi Buffon to get the trophy.
Each of Ronaldo's honors as the best player in Europe followed Real Madrid winning the Champions League.
"There are the same goals every year, to meet the same challenges, win everything if possible, qualify for the World Cup with my national team," said Ronaldo.
"This trophy will give me the motivation to keep working hard, never to give up. I am blessed and delighted to be with Real Madrid."
Ronaldo won the UEFA award in 2013-2014 and 2015-2016 and in the Champions League last season, where Real defeated Juventus 4-1 in the final, he finished as top scorer with 12 goals.
The Madrid and Portugal star is strongly favoured to get a fifth FIFA world player prize in October.
The UEFA vote by journalists from 55 member federations was announced on Thursday at the Champions League group-stage draw.
UEFA created a European prize after the original Ballon d'Or merged with FIFA's world award.
The women's award was won by Lieke Martens of the European champion Netherlands. The other nominees were Pernille Harder of Denmark, and Dzsenifer Marozsan of Germany.
Real Madrid's Luka Modric won the UEFA Midfielder of the season award while Juventus' Gianluigi Buffon won Goalkeeper of the Year award.