He played college football for the Georgia Bulldogs, and was selected by the Indianapolis Colts in the second round of the 2006 NFL draft.

[5] Jennings signed with the Chicago Bears in free agency and earned a starting position in coach Lovie Smith's defense.

[6] Jennings was part of the team that advanced to the 2010 NFC Championship Game, ultimately falling just short of a berth in Super Bowl XLV.

During a middling 2011 season, Jennings was benched by the Bears coaching staff after a poor game against the Seattle Seahawks in Week 15.

During his time in Chicago, Jennings and hard-hitting Charles Tillman formed one of the best cornerback tandems in the league.

[9] The following week, Jennings recorded five tackles, two passes defended, and intercepted Aaron Rodgers in a 23–10 loss to the Packers.

[12] In Week 13 against the Seattle Seahawks, Jennings sustained a shoulder injury, and was ruled out of the following game against the Minnesota Vikings.