The 22-year-old Ross was inactive for Green Bay's season opener against the 49ers before being waived on Sept. 10. Ross re-signed with the Packers' practice squad two days later, but couldn't turn down the opportunity to rejoin an NFL squad.
A spot on the Raiders 53-man roster opened up after the team waived long snapper Nick Guess on Tuesday.
The 6'1, 191-pound Ross was an undrafted free agent from Youngstown State in 2011 and played with Green Bay's practice squad for the entirety of the 2011 season.
Oakland also signed a pair of players to their own practice squad on Wednesday in defensive back Akwasi Owusu-Ansah and defensive tackle Vaughn Meatoga.
The Raiders currently rank 15th in the league in yards per game after their two losses this season.