"Seydou Keita has announced tonight he will not continue with the club next season," Barca said on their website.
"Barcelona thanks Seydou Keita for his contribution over the past few years and wishes him more professional and personal success in the future."
He had a close relationship with Guardiola and his exit is likely to be linked to the former Spain and Barca midfielder's decision to quit at the end of last season.
Guardiola used Keita almost exclusively as a substitute and the player helped Barca win three Spanish leagues, two Champions Leagues and two King's Cups.
Spanish media reported the midfielder had a clause in his contract, which runs until 2014, that allowed him to leave on a free transfer if he did not start at least half of last season's games.
Keita has been linked him with a move to Chinese Super League club Dalian Aerbin.