Souleymane Diawara is expected to join Bordeaux on Wednesday after he passes a medical at the Stade Chaban Delmas.
Bordeaux are understood to have agreed a 4million euros (£2.7million) deal with Charlton, while also reaching an accord on personal terms with the defender.
Diawara is putting the finishing touches to his move back to France after just one disappointing season with The Addicks.
The former Sochaux stopper should seal the switch to Bordeaux later on Wednesday, to the delight of Les Girondins coach Laurent Blanc.
"It is a great satisfaction, because the signing of Diawara was a repeated wish from the coach," chairman Jean-Louis Triaud told French media.
"Even if Blanc had other options he favoured a player with experience and strength.
"With this signing our summer reinforcements will be definitely over."
Fernando Menegazzo has signed a one-year contract extension with Bordeaux, keeping him at the club until 2011.
Former Bordeaux coach Ricardo had been linked with a bid to take the Brazilian to Monaco, but Menegazzo will be staying with Les Girondins.
"Bordeaux are happy to announce the contract extension of Fernando Menegazzo," said a club spokesman.
"The Brazil international, who recently won the Copa America, has chosen to sign for an additional year.
"He is now under contract until June 2011."