The Seahawks announced that move Tuesday; they also signed defensive back Ryan Neal to their 53-man roster and linebacker Tim Williams to their practice squad. Seattle still has one open spot on its 53-man roster.
A first-round drat pick by the Packers in 2015, Randall has made 56 career starts, including 26 over the previous two seasons with Cleveland. He has played cornerback and safety, two positions where the Seahawks are banged up.
They didn't have starting right cornerback Quinton Dunbar (knee) or backup Neiko Thorpe (hip) for their win over the Dallas Cowboys last week. They lost strong safety Jamal Adams late in the game to what coach Pete Carroll has called a first-degree groin strain and were playing without one of his backups, Lano Hill (hip).
Carroll credited general manager John Schneider for the addition of Randall.
"For us to be able to pick him up under these circumstances with guys being banged up and when there's some uncertainty here, that's a great job by John to figure that out how to get him here and all that," Carroll said. "He looked good in the workouts, and we'll see what happens as our needs present themselves this weekend."
Carroll said Adams is "pretty sore" and that the Seahawks will go day-to-day with him to see about his chances of playing Sunday at the Miami Dolphins. Hill hasn't fully recovered from the hip injury that kept him out last week, "but he's looking toward playing" Sunday, Carroll said.
Meanwhile, Carroll said he thinks Dunbar is improving and has a chance to play Sunday, but added that Dunbar wouldn't practice Wednesday.
The Seahawks have allowed a league-worst 430.7 passing yards per game.
Neal replaced Adams and sealed Seattle's win with an interception of Dak Prescott in the end zone on Dallas' final play. He and linebacker Shaquem Griffin had been elevated just for game day, which meant they automatically reverted to Seattle's practice squad on Monday.
Carroll has said Griffin earned an opportunity to play again at Miami after his strong showing in 17 defensive snaps against Dallas. It's not clear if he will be signed to Seattle's 53-man roster or elevated again just for game day. The Seahawks protected Griffin and tight end Stephen Sullivan on their practice squad, meaning those two players can't be signed by other teams this week.
Griffin and Williams give Seattle depth at linebacker, another position hit hard by injuries. The Seahawks lost Bruce Irvin to a season-ending ACL tear in Week 2. Brooks, their first-round pick, was making his first career start when he injured his knee against Dallas.
Williams, a third-round pick by the Baltimore Ravens in 2017, has appeared in 20 games with no starts.
Outside of the secondary, the Seahawks also lost running back Chris Carson and linebacker Jordyn Brooks to what Carroll called first-degree knee strains, while right guard Damien Lewis sprained an ankle.
Carroll said none of those injuries appears serious enough to bring injured reserve into play, but he said "it's going to be a real challenge" for Brooks to play Sunday. He's more optimistic with Carson and Lewis, who both took part in Wednesday's walk-through.