Oakland announced the transaction on Tuesday. The Lions waived safety Tevin Mitchel with an injury designation in a corresponding move.
Davis was an undrafted free agent signing this offseason by the Lions. He spent time with the NFC North franchise throughout its offseason program and training camp. The 5-foot-11, 196-pound defender had two tackles in two preseason appearances for Detroit. The Lions waived Davis on Monday.
Davis had 50 tackles, three forced fumbles, two interceptions, a sack, an interception for a touchdown, a pass defensed and a fumble recovery in 23 collegiate contest at Texas.
The Raiders' unofficial depth chart lists Rashaan Melvin and Gareon Conley as the team's starting cornerbacks. Leon Hall and Daryl Worley are listed as second string options. The Raiders also have Shareece Wright and Nick Nelson at the position.
Oakland hosts the Green Bay Packers in its final preseason game at 10:30 p.m. on Friday in Oakland.