Jennings played college football at the University of Miami, where he graduated with a degree in finance and a 3.0 grade point average.

He ended up playing in 16 games, starting in 2, recording 40 tackles, 1 interception, 6 passes defended, 1 forced fumble, and giving up 2 touchdowns.

In the postseason, with Seattle's secondary seriously hurting and forced to start safety Jordan Babineaux at #2 CB and previously out of the NFL Pete Hunter at nickel, Jennings was forced into the #1 role for the Wild Card game against the Dallas Cowboys and was primarily used to cover Terry Glenn due to their similar body build and playing styles.

In the Divisional Playoff game against the Chicago Bears, Jennings recorded 6 tackles but was beat deep on a 68-yard touchdown pass from Rex Grossman to Bernard Berrian.

Coming into the 2008 season, Kelly had high expectations, but was moved to the nickelback and performed well once again at a position he has proven to be more than capable at.