Monday's signing fill Seattle's need for more size in the secondary.
The team also announced it signed veteran fullback Justin Griffith. Both get one-year contracts.
Lucas began his career in Seattle as its second-round pick in 2001. He signed with Carolina as a free agent after the 2004 season and played four seasons there. The Panthers released him last month in a salary-cap move.
He has played in 122 career games with 106 starts, 24 interceptions and 100 passes defensed.
Griffith was drafted by Atlanta in the fourth round in 2003. He spent four years with the Falcons before signing with Oakland in 2007.
Copyright 2009 by The Associated Press