He played college football for the North Carolina Tar Heels and was selected by the Tennessee Titans in the second round of the 2012 NFL draft.

Brown also ran track and field for the North Carolina Tar Heels, where he recorded a personal best time of 6.72 seconds in the 60 meters.

Brown was also an accomplished High School wrestler, finishing his senior season with state, region and county championships in the 215 lb weight class.

[13] Head coach Mike Munchak named Brown the backup weakside linebacker, behind Will Witherspoon, to begin the regular season.

[15] Brown finished the Titans’ 38–10 loss at the San Diego Chargers with ten combined tackles (six solo) and also recorded his first career sack.

[16] On November 11, 2012, Brown recorded four solo tackles, deflected a pass, and made his first career interception during a 37–3 victory at the Miami Dolphins in Week 10.

On December 30, 2012, Brown made four combined tackles, three pass deflections, one sack, and returned two interceptions by Chad Henne for two touchdowns during a 38–20 win against the Jacksonville Jaguars in Week 17.

Brown intercepted a pass by Henne, that was intended for tight end Marcedes Lewis, and returned it 79–yards for his first career touchdown during the second quarter.

[19] Brown entered training camp slated as the starting weakside linebacker after Will Witherspoon departed for the St. Louis Rams during free agency.

Head coach Mike Munchak named Brown and Akeem Ayers the starting outside linebackers to begin the regular season.

[22] Brown was moved to inside linebacker and competed for a starting role against Wesley Woodyard, Colin McCarthy, Moise Fokou, Zaviar Gooden, and Avery Williamson.

[25] Brown started in the Tennessee Titans’ season-opening 26-10 victory at the Kansas City Chiefs, but exited in the first quarter after injuring his shoulder.

[27][28] Throughout training camp, Brown competed against Wesley Woodyard and Avery Williamson to regain his role as a starting inside linebacker.

[32] Brown finished his last season with the Tennessee Titans with 77 combined tackles (55 solo), three pass deflections, two interceptions, and was credited with half a sack in 16 games and five starts.

On October 2, 2016, Brown collected a career-high 17 combined tackles (12 solo) and made one sack in the Bills' 16–0 victory at the New England Patriots in Week 4.

[40] Brown started in all 16 games for he first time of his career and recorded a career-high 149 combined tackles (97 solo), four pass deflections, four sacks, two forced fumbles, and one interception.

[41] On January 23, 2017, it was announced by the NFL that Brown was selected to play in the 2017 Pro Bowl as a late replacement for New England Patriots' linebacker Dont'a Hightower.

Head coach Jay Gruden named Brown and Mason Foster the starting inside linebackers to begin the regular season.

On December 10, 2017, Brown made ten combined tackles (five solo), but was carted off the field in the fourth quarter of the Redskins’ 30–13 loss at the Los Angeles Chargers due to a foot injury.