The Hurricanes also added Virginia transfer Justin Renfrow and junior-college transfer Ufomba Kamalu.
Gilbert thought his playing career was over earlier this year because of recurring right-foot injuries. He had seven sacks and 52 tackles in his final 18 games at Wisconsin.
Renfrow played in 12 games for Virginia last season. He and Gilbert are eligible to play right away because they graduated from their previous schools.
Kamala signed with Miami in February out of Butler Community College. He was able to practice with Miami for the first time Saturday.