[12] Head coach Dan Quinn named Campbell the starting weakside linebacker to begin the regular season, alongside Deion Jones and Vic Beasley.

[13] Campbell made his professional regular season debut and first career start in the season-opener against the Tampa Bay Buccaneers and recorded four solo tackles in the 31–24 loss.

[14] On October 23, 2016, Campbell collected a season-high ten combined tackles (six solo) during a 33–30 overtime loss to the San Diego Chargers in Week 7.

[16] Campbell finished his rookie season with 48 combined tackles (35 solo), seven passes defensed, a forced fumble, and an interception in 11 games and 10 starts.

On January 14, 2017, Campbell started his first career playoff game and recorded four combined tackles during a 36–20 victory over the Seattle Seahawks in the NFC Divisional Round.

On February 5, 2017, Campbell started in Super Bowl LI and recorded four total tackles as the Falcons were defeated 34–28 by the New England Patriots in overtime.

[19] On February 8, 2017, the Falcons fired defensive coordinator Richard Smith after they lost a 28–3 lead in the Super Bowl and allowed the Patriots to score 31 points in the second half of the game.

[21] Campbell entered training camp slated as the starting strongside linebacker after Vic Beasley was moved closer to an edge rushing defensive end role.

[33] On January 14, 2022, Campbell was named a first-team member of the 2021 All-Pro Team, becoming the first Packers inside linebacker to achieve this honor since Ray Nitschke in 1966.

[35][36] On October 23, 2022, during a Week 7 loss to the Washington Commanders, Campbell intercepted a pass from Taylor Heinicke and returned it 63 yards for his first NFL touchdown.

[41] With Greenlaw and Dee Winters experiencing injuries, the team asked Campbell to enter the game, but he refused and later left for the locker room in the second half as the 49ers lost 12–6.