Brown has been a free agent since the Bengals released him last week. The defender was nine games into a three-year, $16.5 million contract that he signed with Cincinnati this past off-season.
The Raiders, who are 6-4 and have won three consecutive games, believe Brown can make an impact in the team's 4-3 base defense. Oakland has been without middle linebacker Vontaze Burfict, who was suspended by the NFL for the remainder of the season after an illegal hit in Week 4.
"He's 27 years old," Raiders head coach Jon Gruden told reporters Monday. "We really liked him coming out of Louisville. He had [four] straight 100-tackle seasons as a Buffalo Bill, went to Cincinnati and, obviously, things didn't work out.
"But he has the intangibles, first of all, that you look for in a middle linebacker. He's charismatic, he's intelligent, a physical guy, football junkie and he's been productive in the league. We'll put him in the room with [linebackers coach David] Lippincot and [defensive coordinator Paul] Guenther and see if he can get caught up quickly and we'll try to fast-track him."
The Bills originally selected Brown in the third round of the 2014 NFL Draft out of Louisville. He led the league with 144 total tackles in the 2017 campaign.
In nine games (eight starts) with the Bengals this season, Brown recorded 54 total tackles, one forced fumble and a fumble recovery.
The team announced that wide receiver and return specialist Dwayne Harris was placed on season-ending injured reserve in a corresponding roster move. He was limited to only three games due to ankle and foot injuries.