Undrafted out of Troy in 2011, Mario Addison spent his first two years in the league bouncing around practice squads and brief stints with Chicago, Indianapolis, and Washington. That nomadic start came to an end in December 2012 when the Carolina Panthers claimed him off waivers, setting the stage for one of the most remarkable developmental success stories in franchise history.

Initially brought in as a situational pass-rush specialist, Addison relied on a lightning-quick first step, low edge leverage, and a relentless motor to collapse pockets. Despite starting just three total games over his first four full seasons in Charlotte (2013–2016), Addison became a lethal third-down disruptor. He chipped in 2.5 sacks in 2013, 6.5 in 2014, and 6.0 in 2015 while helping propel Carolina to Super Bowl 50. In 2016, his role expanded even further as he led the team with 9.5 sacks despite coming off the bench for most of the year.

That breakthrough earned Addison a long-term extension and a full-time spot in the starting lineup beginning in 2017. He rewarded the Panthers with three consecutive double-digit or near-double-digit sack campaigns as the premier pass rusher on the edge. From 2017 through 2019, Addison anchored the perimeter with consistent pass-rushing production, recording 11.0 sacks and 11 tackles for loss in 2017, followed by a 9.0-sack campaign with 11 tackles for loss and three forced fumbles in 2018. He capped his tenure in Charlotte with 9.5 sacks, a career-high 16 tackles for loss, and two forced fumbles during his final season in 2019.

Addison entered free agency and signed a multi-year deal with the Buffalo Bills, reuniting with former Panthers head coach Sean McDermott and general manager Brandon Beane. He later spent time with the Houston Texans before wrapping up his 12-year NFL career.  As a Panther, Addison played in 111 regular-season games (40 starts) and eight postseason contests. He logged 225 total tackles, 55.0 sacks, 49 tackles for loss, 103 QB hits, 11 forced fumbles, and three fumble recoveries.