The 23-year-old, who has won four caps for the west African country, has signed up on a free contract, having helped second division Augsburg win promotion this season.
Stuttgart, who play Bayern Munich on Saturday in their final league game of the season, will be without captain Matthieu Delpierre for up to five months after the French defender injured his hip on Thursday.
He hurt himself in sprint training and will undergo surgery on Friday.
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