"I'M COMING HOME!!!! #FlyEaglesFly," he tweeted.
Reddick agreed to a three-year, $45 million contract with $30 million fully guaranteed at signing, sources told ESPN.
The Eagles' pass rush, which ranked 31st in the NFL last season with 29 sacks, gets a major boost with the signing of Reddick, who has racked up 23.5 sacks over the past two seasons.
Some in the organization think Reddick will fill the pass-rushing strongside linebacker role introduced by defensive coordinator Jonathan Gannon last season as part of his hybrid defense. Genard Avery and rookie Patrick Johnson manned that position in 2021 with limited success.
Reddick, 27, proved last season that his 12.5-sack season with Arizona in 2020 wasn't a fluke. He led the Panthers in sacks with 11, tied for the team lead in quarterback hits with 18 and was second in tackles for loss with 12.
Reddick, who played for Carolina coach Matt Rhule at Temple, embodied everything Rhule wants in terms of toughness and work ethic.
The biggest question about whether to re-sign him was money, with Carolina having only $18.4 million in cap space after the season.
Defensive coordinator Phil Snow also said late in the season he wanted Carolina to get bigger up front, which would allow him to play more 4-3 schemes and be more effective against the run. Reddick played at 235 pounds last season but said one of his offseason goals was to add 10 to 15 pounds for 2022.
Reddick has 31 sacks and 50 quarterback hits in five seasons since being selected 13th overall by the Cardinals in the 2017 NFL draft.
ESPN's Tim McManus and David Newton contributed to this report.