The 24-year-old, who has scored nine times this season, has not started for Nigel Clough's men in 2013 and has been on the substitutes bench for their last 10 matches.
The Jamaica international returns to a club where he scored 16 goals in 45 matches between July 2009 and January 2011 before moving to Millwall.
"Theo gives us another dimension in our attacking options, particularly with Jermaine Beckford on the sidelines at the minute; his availability comes at a good time for us," manager Mark Robins told Town's official website.
"He has a proven goal threat at Championship level, as you can see from his record. I've seen him play for Derby this season and he's played well for them, scoring a few when used as a starter and also off the bench. He has the ability to score a goal.
"Our supporters will be very familiar with him and know that he is pacey, direct and works hard. I'm looking forward to having him in the building tomorrow and working with him."
Robinson's loan includes a recall clause after the first 28 days of the agreement have passed.
- Sports & Recreation
- Nigel Clough
- Jermaine Beckford