Jefferson, who made the shift to free under new defensive coordinator Mike Stoops after working at nickel and Sam linebacker for Brent Venables, led the team last year with four interceptions, including a single-game record three against Ball State.
He also tallied 74 total tackles, including 7.5 for loss and 4.5 sacks.
In addition to that, he managed three pass breakups and a forced fumble while starting 12 of 13 games.
He was an honorable mention All-Big 12 selection by both the Associated Press and coaches after winning Big 12 Defensive Freshman of the Year the previous season.
The award, given to the player deemed college football's best defensive back, is presented by the Oklahoma City-based Thorpe Association in honor of the great Jim Thorpe, who excelled in numerous sports and won gold in the decathlon and pentathlon at the Stockholm Olympics, which have their 100-year anniversary this year.
A winner will be selected from three finalists and will be announced at The Home Depot College Football Awards on Dec. 6 on ESPN.