Campbell will now remain with the Rams until January 31, although under the terms of the agreement he will not be able to feature in Saturday's FA Cup third-round tie at Millwall.
"We are pleased DJ has agreed to stay, he has done a good job for us over the past month and has injected some pace into our frontline," said Derby manager Nigel Clough.
Campbell marked his first appearance for Derby with an injury-time equaliser in a 2-2 home draw against West Brom on December 5. He has made a further five appearances for the Rams.
Clough is also hoping to extend striker Paul Dickov's loan stay from Leicester as well.