This article develops a new theoretical approach to digitalisation in diplomacy, resituating conventional understandings of the relationship between diplomacy and technological transformation. Challenging the conception that ‘traditional’ diplomacy is being supplemented or challenged by new forms of ‘digital diplomacy’, we show how the ubiquity of digital devices and technologies makes disentangling analogue from digital diplomatic practices practically impossible today. The argument is developed through ethnographic observations of everyday diplomatic work in the European Union (EU) multilateral setting in Brussels as well as interviews with ambassadors, attachés, seconded diplomats, spokespersons and interpreters. To understand the place of digital technologies in diplomatic work, we develop the concept of blended diplomacy by which we mean the dual process of the entanglement of technical and social doings and the contestation regarding how this entanglement impacts professional diplomatic imaginaries and relations. Drawing on insights from practice theory and the sociology of science, technology and professions, we show how diplomatic actors demarcate their professional territory and protect their positions through boundary work. They draw horizontal boundaries between what they see as ‘real’ diplomatic work and distractions and vertical boundaries between themselves and other diplomatic actors, ranking people around status and skills. Overall, digital technologies are implicated in deeper struggles regarding what it means to be a diplomat. A focus on the blended character of diplomatic practice opens new avenues for research on how digitalisation, in contradictory and uneven ways, shapes norms, identities, and social relations and how it – through reflexivity, anxieties and contestation – may shape international politics.