Practitioners and scholars are increasingly aware that an array of new actors, communication technologies, agendas and expectations are changing the institution of diplomacy. How diplomatic actors are known and experienced through their representation assumes an increasingly important, and uncertain, role. This article argues that these changes to the field should be considered in terms of the shifting ontological and epistemological conditions for representing and experiencing diplomatic identities. In support of this, the article investigates the influence of mediated communication upon the production of knowledge and the ability to experience others through use of the term ‘mediatization’. Mediatization refers to the ways in which communication technologies have become so integrated into everyday activities that our knowledge and experience of the world is significantly altered, often in ways that appear banal and taken for granted. In the diplomatic context, mediatization involves placing pressure on actors to negotiate issues and identity salience in new ways; to coordinate and negotiate over codes and norms for representation within different mediated environments; and to strategically manage identities, messages and representational modalities within objective-led campaigns. This analysis is used to question further the relationship linking communication, diplomacy and public diplomacy, with the conclusion that public diplomacy can no longer be considered as entirely external communicative activities attached to the diplomatic world, since these are — in an age of mediatization — necessarily part of diplomacy proper. Rather, public diplomacy makes most sense in that coordinating role, as a form of semiotic and normative coalition-building within organizations and among connected stakeholders.