This study investigated the impact of fuel subsidy expenditures on government fiscal deficits in Nigeria from 2015-2022 using quarterly time series data. Autoregressive Distributed Lag (ARDL) modeling was utilized to estimate the relationship between fuel subsidies, fiscal deficit, GDP growth, and inflation. The results provide evidence of a statistically significant positive association between fuel subsidy spending and fiscal deficits in both the short and long-run. A 1% rise in fuel subsidies was linked to a 0.32% increase in the deficit over the long-term. Economic growth was found to have a robust negative relationship with fiscal deficits. However, the connections between inflation and deficits were ambiguous. Diagnostic tests confirmed the stability and explanatory power of the models. Given the sizable fiscal burden imposed by fuel subsidies, the study recommends a gradual, structured reduction in subsidies over a defined timeline combined with policies to accelerate broad-based economic growth. Fiscal rules, improved subsidy targeting, periodic price adjustments, and anti-corruption measures are also advised. The findings highlight the need for fuel subsidy reforms as part of broader efforts to strengthen fiscal sustainability and provide a supportive environment for diversified, sustainable and inclusive growth in Nigeria.