This study examines the relationship between cost of governance and public infrastructure financing in Nigeria over the period 1990–2025. Rising governance costs have increasingly attracted policy concern in Nigeria due to the growing share of public resources devoted to recurrent expenditure while infrastructure deficits continue to widen. The study therefore investigates how key components of governance expenditure influence government investment in infrastructure development. Specifically, the study considers personnel cost, debt servicing expenditure, and administrative or overhead expenditure as proxies for the cost of governance, while capital expenditure on infrastructure serves as the dependent variable. The study adopts a time series research methodology and utilizes secondary data obtained from the Central Bank of Nigeria Statistical Bulletin and publications of the National Bureau of Statistics. The data were analyzed using both descriptive and econometric techniques. Trend analysis through line graphs was used to examine the behaviour of the variables over time, while descriptive statistics were employed to summarize their statistical properties. The stationarity of the series was tested using the Augmented Dickey-Fuller unit root test to avoid spurious regression results. The Autoregressive Distributed Lag (ARDL) modelling approach was then applied to examine the dynamic relationship between governance expenditure and infrastructure financing in both the short run and the long run. The empirical results reveal that components of governance expenditure exert significant dynamic effects on infrastructure financing in Nigeria. Personnel cost shows mixed but significant effects across different lag periods, indicating that rising wage bills can constrain infrastructure spending in some periods while adjustments occur over time. Administrative expenditure exhibits a positive relationship with infrastructure financing, whereas debt servicing expenditure shows a negative relationship, suggesting that rising debt obligations may reduce funds available for infrastructure development. The study concludes that the increasing cost of governance poses a challenge to sustainable infrastructure financing and recommends stronger fiscal discipline, improved expenditure management, and prioritization of capital investment in infrastructure to support long-term economic development.