He went into his first season at Abilene Christian listed as a backup wide receiver, but he quickly moved into a starting role.

He finished third in Division II in 2007 in touchdown receptions, while racking up the fourth-most receiving yards in a season in Abilene Christian history.

Knox helped Abilene Christian start 11–0 before losing in the third round of the Division II playoffs.

His 30 touchdown receptions in two seasons were the most in Abilene Christian history, and he earned second-team All-America honors in 2008.

[2] Knox joined the Chicago Bears after being chosen in the fifth round of the 2009 NFL draft with the 140th overall pick.

On November 29, 2009, Knox returned a kickoff 77 yards to set up a Bears field goal versus the Vikings.

[4] On January 25, 2010, Knox was selected to the NFC roster for the 2010 Pro Bowl, replacing Minnesota's Percy Harvin, who withdrew due to injury concerns.

[4] On December 18, 2011, Knox sustained a serious spinal cord injury during a game against the Seattle Seahawks.

[8] Knox required immediate surgery to stabilize an injured vertebra, but maintained sensation in all limbs following the incident.