Cameron has spent the last six seasons at Stoke, with a total of 186 appearances being made for the Potters in all competitions.
However, the United States international dropped down the pecking order after the arrival of Gary Rowett, and the player has revealed that he jumped at the chance of a new challenge at QPR.
The 33-year-old told the club's official website: "I'm extremely excited and happy to be here. It's a fresh start and new beginning for me.
"I decided over the summer that I wanted a change and something new. The boss [Steve McClaren] here has been interested in me before and I'm excited to play for him.
"He wanted me here which is always a big part when they believe in your ability. I want to help the team and get us up the table."
Cameron could feature when QPR face Birmingham City on Saturday afternoon.