As a senior, Brown played and started 12 games and led the Bruins with 119 tackles, which tied for 16th on the all-time school single-season list.

[10] During training camp, Brown competed for a role as a backup inside linebacker against Daren Bates and Nate Palmer.

[11] Head coach Mike Mularkey named Brown the primary backup inside linebacker to begin the regular season, behind starters Wesley Woodyard and Avery Williamson.

[15] Brown was used extensively in nickel packages as a rookie under defensive coordinator Dick LeBeau due to his athleticism and tackling ability.

Throughout training camp, Brown competed to be a starting inside linebacker against offseason acquisition Will Compton and first-round pick Rashaan Evans.

[22] Head coach Mike Vrabel named Brown the backup inside linebacker to start the regular season, behind veterans Wesley Woodyard and Will Compton.

[23] On September 30, 2018, Brown earned his first NFL start and recorded ten combined tackles (six solo) and one sack during a 26–23 overtime victory against the Philadelphia Eagles.

The following week, Brown collected a season-high-tying ten combined tackles (eight solo) and another sack as the Titans lost 13–12 at the Buffalo Bills.

After a Week 8 bye, Brown made four combined tackles and strip-sacked on quarterback Dak Prescott to mark the first of his career during a 28–14 win at the Dallas Cowboys.

[25] In the regular-season finale against the Colts, Brown had his first NFL interception by picking off Andrew Luck and returned it 22 yards for a touchdown.

During Week 14 against the Raiders, he recovered a fumble forced by teammate Tye Smith on tight end Darren Waller and returned it for a 46 yard touchdown in the 42–21 road victory.

[27] Brown finished his third season with 105 tackles, a sack, eight pass deflections, an interception, and a fumble recovery returned for a touchdowns in 14 games and starts.

[30] In Week 9 against the Chicago Bears, Brown recorded a team high 11 tackles, sacked Nick Foles once, and forced a fumble on wide receiver Anthony Miller that was recovered by the Titans during the 24–17 win.