The 26-year-old from Wake Forest was placed on the PUP list at the end of July, and to make room for his return, Oakland waived linebacker Vic So'oto.
So'oto played in four games for the Raiders this season and recorded one tackle.
Curry has yet to play this year and is not completely healthy. He has sat out with knee problems and head coach Dennis Allen told SFGate.com that Curry has been in the process of working his way back into practices during the past three weeks.
Curry's status on the PUP list would have put him on the injured reserved for the rest of the season had Oakland not activated him by Wednesday, meaning Allen believes he will serve as a backup at the least.
In 2011, Curry played in 11 games for the Raiders after being acquired in a trade from Seattle. He recorded 46 total tackles in those 11 games.