Powell is Alan Curbishley's first signing since his side were promoted to the Premier League by beating Sunderland in the play-offs. The 28-year- old defender began his career in south London with Crystal Palace and then Southend.
Richard Murray, the chairman of Charlton plc, said: "Chris is a quality player with two full years in the Premier League. His experience will be invaluable to us."
Derby have already lined up a replacement for Powell. They expect the German defender, Stefan Schnoor, to complete his transfer from the Bundesliga club Hamburg to Pride Park today.
The 27-year-old, who is moving to Pride Park on a free transfer under the Bosman ruling, is due to have a medical this morning. Schnoor, like Powell, a left-back or left wing-back, agreed personal terms with the Rams before he went on honeymoon to the United States.
Schnoor represents another step in Jim Smith's process of reshaping his side ready for the new Premiership season. The Derby manager is resigned to a close season of wheeling and dealing in the transfer market after setting a club record by paying pounds 2.7m for the Argentinian Horacio Carbonari.Reuse content