The 33-year-old defender signed for the French club on Tuesday has refused to travel on Arsenal’s pre-season tour to the USA as he tried to secure a transfer.
His unveiling video also angered some Gunners fans – and former striker Ian Wright – after he took off an Arsenal shirt to reveal a Bordeaux strip underneath.
Koscielny wrote on Instagram: “After nine years spent at Arsenal, I took the decision to leave. I have spent wonderful years with this club, nine years during which I learned, evolved, grew up.
“This experience made me the player I am today. My decision to leave has been discussed for months with my club, my team-mates, my coach, and it has been a well-thought decision.
“I see this departure like a new turning point in my life as a player but also in my life as a man and a family man.
“However I hope you understand, and in any case, I cannot be thankful enough for these years past at Arsenal. I am aware of everything that the club and your supporters have brought to me.
“But it is time for me to go home so today my will is to join the @girondins (Bordeaux). This is a new challenge that I count on taking with determination.”
