UEFA says the winner will be decided by a media panel on Aug. 25 at the Champions League group-stage draw in Monaco.
Messi scored 53 goals as he and Xavi led Barcelona to the Champions League and Spanish titles last season.
Ronaldo scored a league-record 40 goals for runner-up Real Madrid, which lost to Barcelona in the Champions League semifinals.
The panel of one journalist from each of Europe’s 53 soccer nations elected the three finalists.
UEFA created the honor after “France Football” magazine combined its traditional European award with FIFA’s world player prize.