Oregon coach Chip Kelly said Saturday the 6-foot-6, 204-pound Georgia native made the decision after emerging from spring drills behind Ducks starter Jeremiah Masoli.
Roper started Oregon's first three games a year ago before suffering a knee injury in overtime at Purdue, forcing him to miss the next four games.
Roper finished last year completing 48 of 91 passes for 610 yards and three touchdowns in six appearances in addition to adding 85 yards and one score on the ground.
Kelly said Roper will be best remembered for guiding Oregon to a 56-21 Sun Bowl win over South Florida in his starting debut to cap the 2007 season.
After redshirting as a true freshman during the 2006 season, Roper will have two years to complete his final two seasons of eligibility. There was no word on where he plans to transfer.