This paper proposes an innovative analytical approach to regionalism promotion by the European Union (EU) in Africa. The approach pursues the dual aim of accommodating African approaches to regionalism in EU foreign policy analysis and of expounding the centrality of diplomacy in negotiating a renewed EU-African Union relationship. The concept of ‘regionalism diplomacy’ brings the negotiated and contentious nature of EU regionalism promotion to the fore. The paper espouses contemporary English School thinking about ‘international society’ and argues that EU regionalism promotion cannot just remain the expansion of European regional international society onto Africa. Instead, EU regionalism diplomacy should acknowledge and incorporate the anticolonial pan-African roots of African regionalism. Overall, the EU should seek a more diplomacy-focused, negotiated Africa-Europe interregional relationship. The paper concludes with an outline of a pan-African approach to regionalism diplomacy and avenues for future research.