The 37-year-old arrived at the Piraeus club in 2019, after playing for Libourne, Marseille, Dynamo Moscow, Lyon and Fenerbahçe in Turkey.
He played 120 matches for Olympiakos, scored 14 goals and made 39 assists.
He enriched his record with three league titles and a Greek Cup.
Mathieu Valbuena, whose contract had expired, was international from 2010 to 2015, before the sextape scandal put an end to his adventure with the Blues.
Involved in this case, Real Madrid striker Karim Benzema has since returned to the France team.
© 2022 AFP