[6] He attended Randolph-Clay High School in Cuthbert, Georgia,[7] where he was a four-sport star in football, basketball, baseball, and track.

As a senior, he earned Class AA All-State honorable mention by The Atlanta Journal-Constitution and Georgia Sports Writers Association (GSWA) after rushing for 1,032 yards, leading the region in scoring with 108 points in the regular season.

[10] On March 22, 2005, Davis attended Georgia's pro day, but opted to stand on the majority of his combine numbers and only ran the 40-yard dash and participated in positional drills.

On August 15, 2005, it was reported that the Carolina Panthers moved Davis to outside linebacker after Brandon Short injured his foot during a preseason game against the Washington Redskins.

[19] On August 20, 2005, starting strong safety Colin Branch tore his ACL during the Panthers’ 27–21 loss at the New York Giants in their third preseason game.

Defensive coordinator Mike Trgovac opted to move Davis back to strong safety as a replacement for Branch.

He made his professional regular season debut and first career start in the Carolina Panthers’ season-opener against the New Orleans Saints and recorded five combined tackles during their 23–20 loss.

[26] Head coach John Fox retained Davis and Na’il Diggs as the starting outside linebackers to begin the season in 2007.

[32] On December 22, 2007, Davis recorded seven combined tackles, deflected two passes, and made his first career interception during a 20–13 loss to the Dallas Cowboys in Week 16.

Davis intercepted a pass by Cowboys’ quarterback Tony Romo, that was originally intended for wide receiver Patrick Crayton, in the fourth quarter.

[33] Davis started in all 16 games in 2007 and recorded 88 combined tackles (72 solo), five pass deflections, three sacks, two forced fumbles, and one interception.

[26] Head coach John Fox retained Davis, Na’il Diggs, and Jon Beason as the starting linebackers in 2008.

In Week 11, he collected a season-high 11 combined tackles (ten solo) and was credited with half a sack in the Panthers’ 31–22 win against the Detroit Lions.

On December 21, 2008, Davis tied his season-high of 11 combined tackles (nine solo) and made one sack during a 34–28 loss at the New York Giants in Week 16.

[36] Head coach John Fox retained Davis, Na’il Diggs, and Jon Beason as the starting linebackers for the third consecutive season.

[37] Davis started in the Carolina Panthers’ season-opener against the Philadelphia Eagles and recorded a season-high 16 combined tackles (14 solo) during their 38–10 loss.

[44] On January 13, 2011, the Carolina Panthers announced the hiring of former San Diego Chargers’ defensive coordinator Ron Rivera as their new head coach.

[54] Head coach Ron Rivera named Davis the backup strongside linebacker, behind James Anderson, to begin the regular season.

[56] Davis was named the starting weakside linebacker in a Week 5 after Jon Beason sustained a shoulder injury and was replaced by Luke Kuechly after being placed on injured reserve on October 24, 2012.

[57] On November 18, 2012, Davis collected a season-high 16 combined tackles (11 solo) during the Panthers’ 27–21 loss to the Tampa Bay Buccaneers in Week 11.

[58] Davis finished the 2012 NFL season with 105 combined tackles (70 solo), three pass deflections, two forced fumbles, and one interception in 15 games and 12 starts.

[26] After three years of injuries, Davis started all 16 games and recorded a career-high 123 tackles and four sacks, in addition to two interceptions and a forced fumble.

[59] In the must-win finale at Atlanta, Davis returned a fumble 33 yards to set up a crucial touchdown that started the rout of the Falcons.

[60] Davis' leadership, play, and consistency was a big contributor in these achievements, along with those same attributes found in Kuechly and tight end Greg Olsen.

[63] On January 31, 2015, Davis was named the 2014 Walter Payton Man of the Year by the NFL, recognizing his off-the-field community service work.

[66] Davis continued his outstanding play during the start of the 2015 NFL season, recording 25 tackles, 1 interception, and 1 forced fumble through just the first three games.

Davis played very well during the Panthers Sunday Night victory over the Philadelphia Eagles recording a season high 13 tackles.

[70] It was Davis' second onside kick recovery of the season, the first coming against the Dallas Cowboys Thanksgiving night game.

[74][75] According to Pro Football Focus, Davis had the second-highest coverage grade of any linebacker in the NFL behind only teammate, Luke Kuechly.

[80] On December 18, 2017, Davis was suspended two games after an illegal helmet-to-helmet hit to Packers wide receiver Davante Adams which caused a concussion.