Lynch, a redshirt sophomore who has two years of eligibility remaining, had a strong finish to the season and was a first-team All-AAC selection. He led the Bulls with six sacks and 12.5 tackles for losses while finishing with 30 total tackles. He also returned a fumble 44 yards for a touchdown in the Bulls' Oct. 12 win at UConn.
"We thank Aaron for his contributions to our program over the past two years and wish him all the best in his future," USF coach Willie Taggart said in a statement. "We look forward to Aaron representing USF well in the NFL."
Lynch had to sit out the 2012 season following his transfer from Notre Dame.
As a member of the Fighting Irish in 2011, Lynch earned freshman All-America honors after leading the team in sacks (5.5) and adding seven tackles for losses, 14 quarterback hurries and one forced fumble. He had a penchant, however, for playing through and after the whistle, drawing six penalties that season.
The Cape Coral (Fla.) native transferred the following spring after experiencing homesickness. Notre Dame went on to reach last season's BCS title game.
With his combination of size, speed and strength, Lynch had been projected as a first-rounder by many draft analysts entering this fall, though his stock has since fallen. Listed at 6-foot-6, 270 pounds while at Notre Dame, Lynch was listed at just 244 pounds by USF at the beginning of this season.
Lynch was rated as ESPN's No. 15 overall prospect in the class of 2011 coming from Island Coast (Fla.) High.