Gallas succeeds the departed Thierry Henry in the role and will be supported by Gilberto Silva and the Ivory Coast's Kolo Toure, who have been handed the joint role of vice-captain, while Jens Lehmann will have a role off the field.
"I feel centre-back is always the best position to lead on the pitch and it is Gallas who has more experience at the back. But Gilberto has always been a great captain and Kolo Toure has stature too.
"As well I made a decision that I want all those experienced players, along with Jens Lehmann, to be involved off the pitch.
"Players like Jens and Gilberto can play the role of a club captain. They can have a very strong impact mentally on the team. I want them to take on that responsibility."