Former second-round pick Dan Cody was cut to make room for Douglas.
The 31-year-old Douglas was acquired for a late-round draft choice in 2009 and a conditional 2010 draft selection.
Douglas was with the Ravens from 2001 to 2004 after signing with Baltimore as an undrafted free agent out of Howard in 2000. Last season, he had 72 tackles and three sacks with the San Francisco 49ers.
At 6 feet 2, 292 pounds, Douglas is capable of playing defensive end or defensive tackle in the Ravens' aggressive scheme. Tampa Bay signed Douglas to a four-year, $10.1 million contract during the offseason, but his playing time dwindled behind Kevin Carter.
Douglas is due a $1 million base salary this season and $2.4 million each in 2009, 2010 and 2011. Douglas started 47 of 48 games for the 49ers under former Ravens defensive coordinator Mike Nolan.
For his career, Douglas has 335 tackles and 19 sacks.
Edwards was placed on injured reserve Tuesday. He started a career-high 13 games last season in relief of an injured Trevor Pryce and had a career-high 58 tackles.
Copyright 2008 by The Associated Press
This story is from ESPN.com's automated news wire. Wire index
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