Globalisation has significantly transformed the nature, scope and operation of modern diplomatic practice. This paper examined how globalisation occasioned a shift from traditional state-centred and predominantly bilateral diplomacy towards more complex, multilateral, economic, cultural and digitally mediated forms of diplomatic engagement. It examined China’s Belt and Road Initiative (BRI) and the Asian Infrastructure Investment Bank (AIIB), as well as South Korea’s Global Korea (Segyehwa) strategy and Hallyu (Korean Wave), to demonstrate how states have strategically employed economic, developmental and cultural resources as instruments of diplomacy. The study further examined the implications of these developments for traditional diplomatic practice and the legal institutions governing diplomatic relations. It identified the increasing role of regional organisations, multinational corporations, non-governmental organisations and other non-state actors; the expansion of diplomatic functions into economic, cultural and development-financed diplomacy; the compression of time and space through digital communication; the emergence of new institutional frameworks; and challenges to the traditional conception of diplomatic immunity and state-centred diplomatic recognition. The study adopted the doctrinal research method, relying on relevant international legal instruments, legislation, judicial decisions, books, journals and other secondary materials. It found that globalisation has not displaced the fundamental principles of diplomacy but has significantly modified the manner in which diplomatic functions are performed. It therefore concluded that traditional legal and institutional frameworks must evolve to accommodate contemporary diplomatic realities while preserving the essential protections necessary for effective diplomatic relations. The study recommended legal and institutional reforms, stronger digital and economic diplomatic capacity, improved engagement with non-state actors, and greater Nigerian participation in emerging multilateral and development-financing frameworks.