He played college football for the Maryland Terrapins, and was selected by the Cleveland Browns in the second round of the 2006 NFL draft.

He also recorded 7.5 tackles for a loss, 2.5 sacks, two interceptions (one returned for a TD), two pass breakups, 10 QB hurries and one forced fumble.

He was named first-team All-America by Collegefootballnews.com and second-team by Rivals.com, also receiving All-American honorable mention by Pro Football Weekly.

Jackson entered his senior year on the preseason "watch list" for the Bednarik, Lombardi, Nagurski and Lott Awards.

Jackson was also named ACC Defensive Player of the Year, joining E. J. Henderson as the only Terps to earn this honor.

His 447 tackles rank fourth on Maryland's all-time record list behind linebackers Eric Wilson (481, 1981–84), E. J. Henderson (473, 1999–2002) and Chuck Faucette (466, 1983–86).

He also joined Ratcliff Thomas (1993–95) and Henderson (2000–02) as the only Maryland players to lead the team in tackles three consecutive seasons.

Jackson posted a career-high 16 tackles at Carolina on October 8, 2006, and matched the total vs. Cincinnati on November 26, 2006.

[14] On June 14, 2010, Jackson signed a one-year, $1.75 million restricted free agent tender to remain with the Browns through 2010.

[16] Jackson finally returned from injury in 2011 after nearly missing two whole seasons in a row and thrived in the Browns new 4–3 defensive alignment.

Where the 3–4 restricted Jackson due to his lack of elite size, the 4–3 gave him more space and room to make a play on the ball-carrier.

[20] As an unrestricted free agent he visited multiple teams, including the Indianapolis Colts, Miami Dolphins, Tennessee Titans, and Denver Broncos.