The team confirmed the agreement Thursday.
Rubin has been a full-time starter for most of his seven-year career, all of it spent with the Cleveland Browns. He started all 59 games he played between 2010-13 and 11 of 13 games last season. He had a career-high 83 tackles and five sacks in 2011, but has not approached those numbers since the Browns switched to a 3-4 defense.
The Seahawks have been seeking depth on the defensive line because of the uncertainty of Kevin Williams' return.