Rethinking Infrastructure Financing in Nigeria: A Theoretical Analysis of Factors Influencing Alternative Financing Selection

Nigeria's infrastructure remains grossly inadequate for a population above 220 million and an economy seeking to diversify beyond oil. Public budgets cannot close a financing gap estimated well above US$3 trillion over two decades, pushing government, multilateral partners, and private capital toward innovative financing mechanisms (IFMs) such as public-private partnerships, Sukuk, infrastructure and green bonds, blended finance, and value-capture instruments. Yet little systematic, theoretically grounded understanding exists of why one IFM is chosen over another at the pre-procurement stage. This paper addresses that gap through a systematic literature review, broadly following PRISMA 2020, of peer-reviewed studies published mainly between 2020 and 2026 in Scopus, Web of Science, and major publisher databases, supplemented by seminal earlier theoretical works. Sixty-nine (69) studies met the inclusion and quality criteria and were synthesized thematically into eight determinant categories: project, financial, institutional, market, environmental, stakeholder, socio-economic, and governance factors (PFIMESSG). Five theoretical lenses (Resource Dependence Theory, Decision Theory, Agency Theory, Stakeholder Theory, and Transaction Cost Economics) are critically examined for their power to explain IFM selection in a shallow, institutionally constrained capital market like Nigeria's. The review finds that existing studies are largely descriptive and project-centred rather than mechanism-centred, and seldom combine multiple theories or multi-criteria decision-making methods in one selection framework. A conceptual framework is therefore proposed, linking project, institutional, financial, and stakeholder determinants to IFM selection criteria and, ultimately, to infrastructure delivery outcomes, moderated by Nigeria's institutional environment. The paper closes with a future research agenda and policy implications for government, quantity surveyors, financial institutions, and private investors seeking a more rigorous, decision-support-oriented approach to infrastructure financing in Nigeria.