It's the franchise's first free-agent signing in 2013.
Hayes, a sixth-round draft pick out of Florida State in 2008, spent four seasons with the Buccaneers before playing last year in Chicago. He played under current Jaguars coach Gus Bradley as a rookie.
Hayes has played in 71 career games with 45 starts. He has 291 tackles, seven sacks, four interceptions, four forced fumbles and one fumble recovery. He started three games and played in 15 last season, totaling 24 tackles.
Hayes could fill the role vacated by Smith, who spent his first nine seasons in Jacksonville and is the franchise's all-time leading tackler. Smith hasn't signed with another team yet.