Nolan, who can play across the backline and in midfield, has been training with the Iron for the past month.
He initially joined Scunthorpe on loan from Preston in the summer of 2010 and made 43 league appearances for the club, scoring one goal. His stay at Glanford Park was made permanent in January 2011.
Nolan has failed to find another club since he was released by former boss Alan Knill last summer.
The 24-year-old goes straight into the squad for Saturday's home League One clash against Crawley.