The 26-year-old has spent four and a half seasons with his current club but is set to join Newcastle's battle to avoid relegation.
He wrote on Twitter on Tuesday night: "Big thanks to everyone who has supported me through the good times and bad times. I thank the leadership of the club and the staff for helping me grow.
"I need a new challenge and therefore I hope that you respect my choice. I will follow all the results of the Girondins (Bordeaux).
"Tomorrow I will be a new player of Newcastle and I am proud. Thanks to everyone....kisses."