Curry, the No. 4 overall pick in the 2009 draft, was acquired from the Seattle Seahawks in a trade that was initially reported Wednesday.
The Raiders dealt draft picks in 2012 and '13 for Curry, who starred at Wake Forest and won the Butkus Award as the nation's top linebacker.
He totaled 156 tackles and 5 1/2 sacks in 35 games for the Seahawks, including 30 starts. The 6-2, 255-pounder had just 22 tackles in five games this season for Seattle.
It was the first deal the Raiders made since the death of longtime owner and general manager Al Davis on Saturday.