The former Aston Villa centre-half has signed a one-year deal with the R's and Redknapp is looking forward to having him at his disposal.
Although Dunne missed all of last season with a hip injury, Redknapp is confident he will be an inspired signing.
"This is a great signing for us. He's a top-class defender and a great guy. He's a good character and just what we need," Redknapp told the club's official website.
"He was [Manchester] City's Player of the Year four years running [from 2004-2008] and he will be fantastic at this football club. He's exactly the type I'm looking for.
"Obviously he had his problems last season with the injury but there's an agreement in place that, if he breaks down, the contract can be ended.
"He's confident he'll be okay and, from our point of view, if he doesn't have any problems with it then we've just signed a very, very good centre-half."