The chapter seeks to discuss how diplomacy operates inside international organizations and how the latter use diplomacy to carry out their aims and goals not only to fulfil their duties but also to become active within the global community engaging with other organizations and non-Member States. Considering that international organizations are made up of sovereign states, the chapter notes the apparent paradox that, while states might not recognize each other other’s independence or even existence, they co-exist and transact together in the context of organizations. It follows that such transactions could very well be different from other kinds of diplomatic engagements. Moreover, the chapter describes how organizations are engaged in multilateral treaty-making (and, in the case of the United Nations, universal norms making) and how they ‘export’ their principles and values, especially as regards human rights, the rule of law, democracy and good governance. The chapter also shows how global (United Nations) and regional organizations (e.g. European Union, African Union, Organization of American States) exhibit a great deal of proficiency in a different kind of diplomacy, namely the peaceful resolution of disputes. Finally, the chapter argues that, while states transfer authority and powers to international organizations by simultaneously limiting their own rights, they still control them; therefore, the role and outcomes of diplomacy exercised by international organizations is often limited by members, who prefer to pursue national diplomacy and foreign policy at the expense of the organization’s welfare.