Manziel, who took the Heisman honors in 2013, joined South Carolina defensive end Jadeveon Clowney as the standouts on the list of players given special eligibility for May's professional draft.
There were 73 underclassmen declared eligible last year, including including running back Eddie Lacy (chosen by Green Bay) and cornerback Dee Milliner (New York Jets).
It was the sixth straight season the number of declarees has increased.
Four players who have graduated and still have eligibility remaining -- including Louisville quarterback Teddy Bridgewater -- were also declared eligible.
Manziel, Clowney and Bridegwater are all expected to be first-round selections.