Hankins played for the Indianapolis Colts last year. He performed steadily in the trenches, but was cut one season into a three-year, $30-million contract after the Colts' new coaching staff made schematic changes to the defense.
Prior to his stop in Indy, Hankins spent four years with the New York Giants. He had a career-high seven sacks in 2014.
The Raiders also agreed to terms Wednesday with fellow defensive tackle Clinton McDonald, according to the 31-year-old's agent. McDonald racked up 29 tackles and five sacks with the Tampa Bay Buccaneers last season.