The 24-year-old defender has been without a club since leaving Scunthorpe last summer.
Signing initially on loan from Preston North End in the summer of 2010, Nolan made 43 league appearances for the club, putting in some standout performances during his loan spell when the club were in the Championship. His stay was made permanent in January 2011.
It boosts United's numbers in defence going into a crucial February period. He goes straight into the squad for Saturday's home clash against Crawley Town.