This article explores the secretive practices of Habsburg envoys in Constantinople during the seventeenth and early eighteenth centuries. While recent scholarship has focused on the highly visible, ceremonial aspects of Habsburg-Ottoman relations—such as grand embassies, ritual gift exchanges, and public audiences—this article shifts the focus toward the “hidden dimension” of diplomacy: secrecy. During the seventeenth century, diplomatic ties between the Habsburg monarchy and the Ottoman Empire became institutionalized, leading to a significant and sustained transfer of knowledge as the imperial court in Vienna increasingly required reliable information on Ottoman affairs. The author argues that secrecy was a core component of this diplomatic work, involving espionage, coded messaging, strategic deception, and the manipulation of information. Using an actor-centered perspective, this study examines how diplomats themselves understood and applied secrecy in their professional repertoire. The analysis highlights how these covert communicative practices were functionally embedded in the envoys’ interactions with both the Ottoman and imperial courts. Ultimately, this work aims to illuminate how clandestine activities were just as integral to inter-imperial relations as their well-documented public counterparts.