The American captain has left Rennais.
Neither the length of the contract nor the transfer fee has been disclosed yet, but France Football reports that an amount in the region of €500,000 has been exchanged between the two clubs.
A statement on Rennes' website reads: "An agreement was reached between Stade Rennais FC and Saint-Etienne for the transfer of defender Carlos Bocanegra."
The 31-year-old signed for les Rouge et Noir from Fulham at the start of the 2008-09 season. Bocanegra skippered the US team at the recently concluded World Cup finals in South Africa.
The versatile defender, who can play either at centre-back or at left-back, is expected to be a key part of Saint-Etienne's defensive unit next season.
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