Florida State said an MRI on Monday revealed a Lisfranc injury.
Jenkins had a sack in Saturday's victory, but left the game in the first half with the injury. He walked to the locker room, putting weight on both feet.
Jenkins had 21 1/2 sacks the past two seasons and returned to Florida State for his senior season.
Jenkins has not taken a redshirt season and could return to Florida State in 2013 or enter the NFL draft.