This article borrows theoretical insights from historical institutionalism to analyse the development of sub-state diplomacy in the South African context. It identifies the political negotiations that allowed South Africa to make a relatively peaceful transition from apartheid to a democratic dispensation as a critical historical juncture that established the institutional pathway on which subsequent political processes would unfold. Although the Constitution that emerged from this historical moment makes room for semi-autonomous sub-national entities with some degree of competences in foreign affairs, it also deferred to the impulses of the ANC for a centralised system of government. The article argues that, in the context of the ANC’s entrenched hegemony in the post-apartheid South African polity, this compromise has translated into a centralised political culture which has shaped the nature, scope, and efficacy of the international involvement of provinces and municipalities. Not only have provincial and local governments been shut out of the foreign policy-making process, but their direct involvement in international relations has also been constrained by the dominant understanding that matters of foreign affairs are the exclusive preserve of the national government. The article concludes by noting that without any significant prospects for a major transformation of the institutional order, provinces like the Western Cape have resorted to creative measures that enable them to by-pass the constraining effects of the system in order to make the most of their international relations