Ronaldo scored 42 goals last season in helping United to win the Premier League title and Champions League trophy.
"It's one of the most beautiful days of my life," Ronaldo said on claiming the award.
"I dreamt of this when I was younger.
"It's a great day for me and my family.
"The Ballon d'or has been won by two great Portuguese players and for me to be part of that history is a great feeling.
"Now I want to win it again."