Barton was issued with the ban as a result of his actions on the final day of last season, when he was sent off for a clash with Manchester City forward Carlos Tevez and responded by lashing out at City players Sergio Aguero and Vincent Kompany before attempting to confront Mario Balotelli.
He was frozen out upon Rangers' return for pre-season training and was not even offered a squad number for the new season, prompting his move abroad.
But any hopes that he might avoid serving his ban after moving to a new country have been dashed by a statement from the French League, the LFP, on Thursday.
The statement, published on both the LFP and Marseille's websites, read: "Upon the transfer of Joey Barton from Queens Park Rangers to Olympique Marseille, the English Football Association transmitted to the French Football Federation the disciplinary sanction he was subject to in the English league.
"In accordance with article 12 of FIFA's Regulations for the Status and Transfer of Players, the sanction is applicable in France.
"Consequently Joey Barton, having served three of his 12-match suspension [in England], is suspended for the next nine games in domestic competition (Ligue 1 and the Coupe de la Ligue)."
The FIFA regulation cited in the statement reads: "Any disciplinary suspension imposed on a player prior to a transfer must be enforced or applied by the new association at which the player is registered.
"The former association is obliged to notify the new association of any sanction in writing and upon issuing the ITC (International Transfer Certificate)."
October 7's grudge match with bitter rivals Paris St Germain is the highest-profile game Barton will miss.
He will also sit out Ligue 1 games against Nancy, Evian, Valenciennes, Troyes, Lyon, Ajaccio and Nice as well as OM's entry into the Coupe de la Ligue in the last 16.
But he will be available for Europa League group games against Fenerbahce, AEL and Borussia Monchengladbach twice in the meantime.