Makoun, 29, joined Aston Villa in 2011 but failed to make an impact and already spent last season on loan at Greek side Olympiakos Piraeus. He has signed for the next two seasons with Rennes.
"Rennes have taken up the option to buy Jean Makoun," the club said on their website (www.staderennais.com).
Rennes are 10th in the French league standings and will face St Etienne in the League Cup final next month.
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