Penisini signed a contract with the Panthers on Monday, Darin Gantt of the team's official site reports.
The 25-year-old Penisini announced his retirement last offseason, but after a year away from football, he's electing to resume his career in Carolina. A 2020 sixth-round pick, Penisini spent his first two NFL seasons in Detroit, recording 49 tackles (23 solo) and a sack in 32 games. Penisini will look to provide depth at nose tackle as Carolina switches to a 3-4 defense.