Minnesota had hoped to redshirt Nelson this season, but top quarterback MarQueis Gray has missed time with knee and ankle injuries, aggravating the latter in last week's loss to Northwestern.
Backup quarterback Max Shortell has struggled in Big Ten games, completing 29-of-52 passes for 300 yards with two touchdowns and three interceptions.
Minnesota released its depth chart Friday, and Nelson was listed as the No. 2 quarterback alongside Gray, with Shortell still as the starter.
ESPN Recruiting rated Nelson as the No. 7 prospect in Minnesota in the 2012 class. The 6-foot-2, 222-pound Nelson earned Mr. Football honors in the state and ESPN Gatorade Player of the Year honors as a senior.