The Panthers made room on the roster Monday by waiving reserve offensive lineman Tim Duckworth.
The 6-foot-2 Thomas was the Redskins' second-round pick in 2008 and has caught 40 passes for 446 yards and three touchdowns. But he failed to impress new coach Mike Shanahan and was dogged with questions about his work ethic. Washington waived him on Saturday.
It marks the second straight week Carolina has claimed a receiver off waivers after picking up David Clowney from the New York Jets.
The Panthers average a league-low 10.4 points a game and were held without a touchdown in Sunday's 23-6 loss to Chicago.