He played college football at Mississippi State and was selected by the Washington Redskins in the second round of the 2015 NFL draft.

[4] Smith appeared in 8 games as a true freshman in 2011 season, recording a forced fumble in a 31–3 win over Ole Miss in the Egg Bowl.

Head coach Jay Gruden named Smith the backup right outside linebacker to start the regular season, behind Murphy, after Junior Galette sustained a season-ending injury.

During the third quarter, Smith recovered a fumble he caused while making his first career sack on quarterback Ryan Tannehill for a 13-yard loss.

Head coach Jay Gruden named Smith the starting right outside linebacker after Junior Galette sustained a torn Achilles during the 2016 preseason.

[25] Smith had a strong performance in the 2017 win against the Arizona Cardinals recording a sack, his second career interception, and a fumble recovery caused by Anthony Lanier.

In 2018, Smith recovered a fumble caused by Ryan Kerrigan in the end zone helping to seal the Week 7 win against the Dallas Cowboys and recording his first career touchdown.

[31][32] In Smith's debut as a Packer in Week 1 against the Bears, he made 5 tackles and sacked Mitchell Trubisky 1.5 times in the 10–3 win.

[38] In the Divisional Round of the playoffs against the Seattle Seahawks, he recorded 2 sacks on Russell Wilson during the 28–23 win, including one at the 2-minute warning in the 4th quarter.

[41] In Week 12 against the Bears on Sunday Night Football, Smith recorded three total tackles (one for loss) and sacked Bears quarterback Mitchell Trubisky once during the 41–25 win; he also recovered a fumble forced by teammate Za'Darius Smith on Trubisky and returned it for a 14-yard touchdown, the second score of his career.