Linebacker Clay Matthews already has changed his profile picture on Twitter, showing him in a Rams uniform with the familiar No. 52.
Matthews reached agreement on a two-year deal with the Rams, via multiple reports.
Matthews, a USC product, lives near the Rams’ training facility.
The Packers’ signings of free agent linebackers Preston Smith and Za’Darius Smith signaled the end of Matthews’ days in Green Bay.
Matthews, 32, spent 10 seasons with the Packers, making 494 tackles and 83.5 sacks.
He played in all 16 games last season, recording a career-low 3.5 sacks.