The study investigated the effectiveness of public health expenditure on Nigeria’s economic growth from 2000 to 2023 using ordinary least square method and Johansen cointegration test with the moderating role of institutional quality and governance quality. The model incorporated key indicators namely government domestic health expenditure, control of corruption, education expenditure, inflation, political stability, personal remittances and the rule of law to examine both the long-run and the magnitude of public health spending’s effect on gross domestic product. The findings reveal a positive and statistically significant relationship between public health expenditure and economic growth. Again, government quality captured through control of corruption significantly strengthens the effectiveness of health spending in promoting economic growth while education expenditures and personal remittances show positive but insignificant effects, inflation and political stability exhibit mixed results. The Johansen co-integration test affirms the existence of a long-run equilibrium relationship among the variables. The Granger causality however indicates no short-run causal relationship between public health expenditure and GDP suggesting that the economic benefits of health investment materialize gradually overtime. Overall, the study underscores the importance of sustained health sector investment and strong institutional frameworks as key drivers of economic performance in Nigeria. It recommends increased public health funding, strengthened governance, improved health infrastructure and enhanced incentives for health professionals to maximize the development impact of public health spending in Nigeria.