The 23-year-old Portugal international - who was also named the Professional Footballers' Association Player of the Year - topped the poll of journalists ahead of Liverpool striker Fernando Torres and Portsmouth goalkeeper David James.
Ronaldo, who also won the accolade last season, netted an outstanding 41 goals during the regular season, including 31 in the Premier League as United beat Chelsea to the title.
The two clubs go head to head in the Champions League final in Moscow next week, and both managers Sir Alex Ferguson and Avram Grant were at the Royal Lancaster Hotel on Thursday evening to see the brilliant winger presented with his trophy.
Ronaldo maintained he had every intention of bettering his performance next season.
Following a tribute from former Manchester United and England midfielder Bobby Charlton, Ronaldo said: "I am very happy to win this award. It is very important for me to win again, but most important is the collective awards (of the team).
"I am still going to want to win more, to carry on like this, I will not stop because I have these two awards.
"Next season I will try to do my best again.
"I have improved every season and will try to improve next season.
"I am enjoying my football, and want to carry on."
well CR7 great balla...needs 2 put down sum lil stuf he does still...diving dis year wasnt dat bad
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I NEVER fail, i'm just SUCCESSFUL in finding out what doesn't work Freedom is never voluntarily given by the oppressor; it must be demanded by the oppressed.
bout divin look pon arsenal man dem u see da one deh cesc a balerina dat enuh but ronaldo nuh dive through di man suh fast any likkle touch wud f*k up his momentum u zimmie lolololand him fall but annno div him dive dk look pan man like drogba