[4][5] After graduating from Brown, he spent some time in New York City, acting in minor theatre productions.

On the DVD commentary for Prison Break, he mentions he had previously auditioned for the roles of Theodore "T-Bag" Bagwell and Lincoln Burrows.

He also appears in Rat Race (2001) as Lloyd (The Hardware Store Guy), and in The Whole Ten Yards as Yermo.

Mitchell also made appearances on CSI: Miami, CSI: NY, Law & Order: Special Victims Unit, Burn Notice as charming but unstable arms dealer Seymour, Dexter, Monk, Six Feet Under, The X-Files, The Closer, and Boomtown.

Mitchell also appeared in Fox's TV show, Mental with Chris Vance, also from Prison Break.