The 24-year old England international was voted the best player for season 2009/10 by his peers, clinching the award from Chelsea's Didier Drogba, Arsenal star Cesc Fabregas and Manchester City's Carlos Tevez.
Rooney adds the triumph to his two Young Player of the Year awards and admitted it was a great feeling to be nominated by the players.
"It's a great feeling to win the Player of the Year award because it's voted for by the players," said Rooney.
"It's something I'm really proud of and it's a great honour.
"I remember coming here in 2005 and 2006 to win the Young Player of the Year.
"I saw the players winning the main one and it's something I've aimed for since."
Rooney also praised United manager Sir Alex Ferguson for helping him evolve his game so much in the past few years.
"Sir Alex is a great manager who has really brought me on as a player since I joined United," he added.
"His hunger passes through to the players. It's great to see that he's pushing 70 and hasn't changed a bit.
"I'm sure he'll be here for a long time yet."