Simpson, who began his career at Manchester United, will join up with his new team-mates on July 1st after the expiry of his Magpies' contract.
And the 26-year-old is relishing the new challenge that lies ahead at Loftus Road after becoming Harry Redknapp's first signing of the summer.
"I want to play week in week out. That was the main thing for me. Harry wants me playing and he wants me involved," Simpson told the club's official website.
"He's a top manager, and as soon as I spoke to him I knew this was the right move for me. I've always admired him. He is a great man in the game and I have a lot of respect for him.
"In training and games, I will give 110%. I know Harry has spoken to other coaches about me and I am sure one thing they would have said is that I am a good pro and that's what he wants in his squad.
"From what I've heard from Harry and the staff I have spoken to, along with some of the players here who I know, they are determined to put things behind them and get back into the Premier League where the club belongs."
Redknapp added: "He's the type we want at the club. He's a good professional, a good character and a good player who knows his job in the side.
"He'll be a really fine acquisition for us. It's a fantastic piece of business for the club on a free transfer."