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.
Seattle also signed defensive tackle D'Anthony Smith, who was with the Seahawks in training camp last year before being placed on injured reserve.
The Seahawks have been seeking depth on the defensive line because of the uncertainty of Kevin Williams' return.
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