This study interrogates the persistence of underdevelopment in Africa’s leading petroleum-exporting economies of Nigeria and Angola through a comparative political economy analysis grounded in Rentier State Theory (RST) and New Institutional Economics (NIE). Despite decades of substantial oil revenues, both countries continue to experience fragile institutions, fiscal volatility, elite rent capture, and limited structural transformation. Drawing on a qualitative methodology and triangulated secondary data from institutional reports, peer-reviewed scholarship, and reputable media sources covering the period 2019–2025, the study demonstrates that oil rents dominate state revenue and export structures in both cases, reinforcing centralized patronage systems, weak accountability, and distorted development priorities. While Nigeria remains characterized by fragmented governance and persistent prebendal politics, Angola’s post-2019 institutional and anti-corruption reforms indicate modest improvements in rent governance. By integrating RST and NIE, the study advances a nuanced explanation of how external rents interact with institutional vulnerability to reproduce uneven development outcomes. The paper concludes that sustainable development in African rentier states requires not only economic reform but fundamental institutional restructuring capable of realigning elite incentives toward productive transformation. Keywords: Rentierism; Development; Nigeria; Angola; Political Economy; Institutions; Oil Economy.
Onya et al. (Wed,) studied this question.