Financial terms were not released Tuesday.
The 6-foot-4, 252-pound Trusnik is an eight-year NFL veteran who spent the last four seasons with the Dolphins. He played in all 16 games in 2014 with five starts. He had 39 tackles, two passes defensed, one forced fumble and two fumble recoveries on defense.
He also had six tackles on special teams.
Panthers coach Ron Rivera says Trusnik is "an experienced player who adds more competition to the linebacker position and has also been a special teams ace. I expect him to come in and be a leader."
Trusnik has also played for the New York Jets and Cleveland Browns, starting 25 career games.