He played college football for the Illinois State Redbirds, and was selected by the Kansas City Chiefs in the fifth round of the 2005 NFL draft.

[1] He came in second behind only future Kansas City Chiefs teammate Jared Allen in the voting for the Buck Buchanan Award, given annually to the top defensive player in Division I-AA.

[1] He was Gateway Football Conference Player of the Year, a Division I-AA All-American and Buchanan award finalist each of his final three seasons.

[3] The transition was chronicled on the HBO reality series Hard Knocks:Training Camp with the Kansas City Chiefs.

[1] Grigsby won the team's starting fullback job in 2008 after incumbent Reagan Mauia was released during final cuts.

However, after starting the Dolphins' season opener against the New York Jets on September 7, Grigsby was released by the team two days later in favor of free agent Casey Cramer.