The Chicago Bears chose him in the first round of the 2004 NFL draft, and he also played a season for the San Diego Chargers.

Harris was born in Nuremberg, Germany, where his father, Tommie Sr, was stationed as a United States Army drill sergeant.

[1][2] Harris and his family relocated often due to Tommie Sr's role in the Army before finally settling in Killeen, Texas.

As a member of the Ellison Eagles, Harris became one of the nation's top defensive high school prospects, including being ranked as the No.

[14] One June 19, 2008, Harris signed a four-year contract extension with the Bears worth $40 million, which made him the highest paid defensive tackle in the NFL.

The Bears suspended Harris for their following game against the Detroit Lions for missing scheduled treatments to rehabilitate his knee without a proper excuse.

[7][18] On November 8, Harris was ejected just 65 seconds into the first quarter in a game against the Arizona Cardinals for punching guard Deuce Lutui in the face.

[20]" The same week, former defensive tackle Warren Sapp criticized Harris, comparing him to "blind dog in a meat house.

[23] Harris signed with the San Diego Chargers on September 28, 2011 to reinforce the team's defensive line following injuries to Luis Castillo and Jacques Cesaire.

[24][25] Harris was the co-owner of the Texas Outlaws of the Fall Experimental Football League along with fellow NFL alum Eric Bassey.

[27] Harris donated $165,000 to pay for new equipment in the Lions Club Park Family Recreation and Senior Center in Killeen, Texas.

[28] Harris was mentored by NFL Hall of Famer Reggie White, whose influence significantly shaped his life and playing career.

[30] In 2017, his agent, William G. Horn, was revealed to be stealing money from Harris' charity and using it for personal expenses, including entertainment and traveling.

[30] Harris published a book about coping with his personal struggles, titled Endure: Playing Through Life's Hardest Hits in 2021.

[30] Harris was arrested in Chicago and charged with indecent exposure, urinating in public and simple assault for threatening a police officer in 2012.