The 32-year-old, who was released by West Ham United at the end of last season, has signed a one-year-contract.
Former England international Dyer told the club's website: "I'm just delighted to be here.
"QPR are an ambitious club. When I sat down with Neil [Warnock] and he explained the vision for the club I wanted to be part of it. He totally sold the club to me.
"I've got something to prove after the couple of years I've had, but I feel good and I'm really looking forward to playing my part next season."
Dyer has been plagued by injury problems in the past but manager Warnock was delighted to sign the former Ipswich, Newcastle and West Ham player.
"When a player of Kieron's ability becomes available, you'd be crazy not to be interested," he explained.
"As far as I'm concerned it's a gamble worth taking. He really impressed me in training and it looks like he has been working hard on his fitness throughout the summer."
Dyer becomes QPR's second signing this week after striker Jay Bothroyd also joined on a free transfer.