Burnett attended Carson High School, before transferring after his sophomore season to Dominguez High School. He played safety and running back while helping his team reach two consecutive playoff appearances. As a senior, he had 48 carries for 650 yards and 16 touchdowns. He was a member of the 1999 Prep Star All-American team, a second-team All-State choice, and a member of the "Best of the West" by the Long Beach Press-Telegram.
College career
Burnett accepted a football scholarship from the University of Tennessee. As a true freshman in 2000, he was switched from free safety to outside linebacker midway through the season and played mainly on special teams. As a sophomore in 2001, he started 2 games, finishing with 52 tackles, 3.5 sacks and 3 passes defensed. In 2002, he was lost for the year after suffering a torn anterior cruciate ligament in his left knee during the season opener. As a junior in 2003, he started 12 out of 13 games, posting 90 tackles, 8 quarterback pressures, 1. 5 sacks and 3 passes defensed. He was named honorable-mention All-SEC and along with Michael Muñoz, became the first Vols juniors since 1944 to serve as team captains. As a senior in 2004, he registered 120 tackles, 6 tackles for loss, 7 special teams tackles, one sack, one interception. Against the University of Florida, he tallied a career-high with 16 tackles. Along with Michael Muñoz, became the first Vols two-time captains since J. G. Lowe earned that honor in 1924-1925. He received first team All-SEC and All-American honors. Burnett was also a semi-finalist for the Dick Butkus and Chuck Bednarick Awards.
Burnett was selected by the Dallas Cowboys in the second round of the 2005 NFL Draft. He played sparingly as a rookie, after having problems with injuries in both of his knees. He was placed on the injured reserve list on December 29, after tearing his right ACL during a practice. He finished the season with 11 special teams tackles. In 2006, he was the backup behind DeMarcus Ware, posting 40 tackles, 16 special teams tackles, one sack, 2 forced fumbles, one interception. The next year, he was a backup at inside linebacker and started 2 games in place of Akin Ayodele. He registered 52 tackles, 46 solo tackles, 18 special teams tackles, 2 passes defensed and one forced fumble. In 2008, he finished with 2 starts, 38 tackles, 2 sacks and 3 passes defensed. During his time with the Cowboys he proved to be a quality backup, that was valuable as a coverage linebacker and special teams player. He played mostly in the nickel and dime defense.
San Diego Chargers
On March 10, 2009, he signed as a free agent with the San Diego Chargers, looking to become a starter. He played in 11 games, posting 66 tackles, 2.5 sacks and one pass defensed. In 2010, he started every game at inside linebacker, finishing with 95 tackles, 6 sacks, 2 interceptions and 2 forced fumbles. He contributed to the Chargers leading the NFL in total defense and pass defense, while ranking fourth against the run.
Miami Dolphins
On July 29, 2011, he signed as a free agent with the Miami Dolphins, reuniting with head coachTony Sparano, who was the offensive line coach during his time with the Cowboys. He started every game, registering 105 tackles and 2.5 sacks. He joined Yeremiah Bell and Karlos Dansby, to mark the first time in franchise history that three players had 100 or more tackles in the same season. In 2012, he had career-highs with 110 tackles, 2.5 sacks and 5 passes defensed. In 2013, after the team signed free agentsPhilip Wheeler and Dannell Ellerbe, he was released on March 12.
Oakland Raiders
On March 17, 2013, Burnett was signed by the Oakland Raiders as a free agent. He started all 16 games primarily at weakside linebacker, finishing with 129 tackles, 2.5 sacks, one interception, 2 forced fumbles and one fumble recovery. Along with his brother Kaelin, they became the first set of brothers in franchise history to play in the same regular-season game. In 2014, after not being able to recover from an injured ankle he suffered in the second organized team activities session, he was waived on July 24.
Burnett is the cousin of Amir Johnson, played forward in the NBA. His brother Kaelin Burnett played linebacker in the NFL. He is a member of the Omega Psi Phi fraternity, initiated Spring 2004 via Iota Beta chapter.
