The 25-year-old told the Rams' website: "I am really excited to join. It is a big, big club. I know the manager [Steve McClaren] well so I cannot wait to get playing.
"He tried to get me at FC Twente, whether it was a loan move or something on a permanent basis I am not too sure, but that didn't quite happen. Then we ran into each other again at QPR, and a transfer didn't quite happen there either. But hopefully this time he has got his player!
"All the managers that you really like, you hope that wherever they go they keep you in mind, and hopefully I can now repay the faith that he has shown in me. You always want to play for a big club and a great manager, and I have that opportunity now, so it is time to repay his faith."
Dawkins has previously had loan spells at Leyton Orient, San Jose Earthquakes and Aston Villa.