Article 27.3(b) of the Agreement on Trade Related Aspects of Intellectual Property Rights (TRIPS) obliges all World Trade Organisation (WTO) embers to protect plant varieties. This thesis unpacks plant variety protection in the Global South, using Nigeria as a case study. To do this, the thesis adopts Third World Approaches to International Law (TWAIL) as a macro-methodological lens and regime complex theory as a supplement. TWAIL is a historically aware methodology that engages with international law from the perspectives and aspirations of the Third World. While regime complex theory illuminates how the overlapping non-hierarchical institutions, agreements, systems, and principles governing plant variety protection shape the implementation of Article 27.3(b) of TRIPS. Combining TWAIL with regime complex theory uncovers the complexities in plant variety protection law-making in the Global South with a view to provide lessons for Nigeria. As Nigeria currently does not have a plant variety protection system, the thesis employs an original empirical study, involving semi-structured iinterviews in Nigeria, to understand realities and stakeholders’ perspectives on the subject. Based on the empirical insights, the thesis proposes a sui generis system which protects the interests of both small-scale farmers and commercial breeders as best suited to Nigeria. To understand the intricacies and contingencies of designing such a system, the thesis examines plant variety protection laws and law-making of Global South WTO members such as the African Group, India, and Thailand. Drawing lessons from this examination, the thesis develops original frames for analysing plant variety protection in the Global South, namely: trade agreements, regional associations, pressures from seed companies, international institutions lobbies, and civil society activism. In combining the original multi-layered methodological lens, empirical study, and analytical framework, the thesis presents the first comprehensive analysis on plant variety protection in Nigeria. It is hoped that this timely thesis will inspire the introduction of the sui generis system proposed.