Starting from the reign of Francis I to that of Louis XIII, the King of France, Europe’s second-most powerful Catholic monarch, bearing the title of “Très Chrétien” (Most Christian King), nevertheless employed several diplomats of the Reformed faith. Among the places where they represented the sovereign, the Swiss embassy stood out as an especially popular post for Protestant agents, especially during the Valois period. As its special ally and main supplier of troops, Helvetia was a particularly strategic place for the security of the French monarchy. While the activity of a representative considered to be Lutheran can be traced back to the 1530s, others later followed discontinuously, also during the Wars of Religion. Such a paradox raises questions: While within the kingdom the Crown opposed the free expansion of the new faith, often violently, it did not seem to have many qualms about using adherents of condemned doctrines to represent it within the Confederacy of the Thirteen Cantons. It is thus worth asking why the Valois kept sending agents with Protestant tendencies to the Confederacy, often knowingly. To address these questions, we will look at these different profiles, and examine the modalities and specifics of the various missions they were entrusted with until the accession of Henry IV.