He played college football as a quarterback for the Missouri Tigers and was selected in the fourth round of the 2006 NFL draft by the New York Jets.

He received numerous national and Big 12 Conference freshman honors, leading the Tigers to a 5–7 record.

In his junior season, he was considered a preseason Heisman Trophy candidate by many, but Missouri and Smith did not live up to expectations, achieving only a 5–6 record.

Through Week 5 of the 2007 season, the Jets used Smith in a variety of ways, lining him up at quarterback, running back, and wide receiver.

Smith would then alternate with former starter Chad Pennington for the rest of the game, running an option and also attempting a pass.

He is also a winner of the Jets' 2007 Kyle Clifton Good Guy Award, which recognizes consistent willingness, cooperation and professionalism in everyday dealings with various departments in organization.

He had been injured (quad) throughout the beginning of the 2009 season, but emerged to become a leader of special teams, including being the starting kick returner.

In the last game of the 2009 regular season, Smith had 91 rushing yards, lining up at quarterback each time, having a 57-yard play, and scoring a 32-yard touchdown.