This study critically examined the impact of public sector financing in the Nigerian economy. The study period covers1990 to 2016. The variables under investigation are Government Capital Expenditure, Government Recurrent Expenditure, Debt Financing, Internal Revenue Generated and Gross Domestic Product. Using Auto Regressive Distributed Lag (ARDL) model the study discovered that government capital expenditure; Debt Financing and Internal Revenue Generated all have a significant impact on the GDP. On the other hand government recurrent expenditure (Administrative cost) have an insignificant impact on GDP. The result further showed that government financing play crucial role in influencing the level of productivity in the country. Following the outcome of the study, the recommendations made include that: Government Expenditure should give priority attention to capital and public investments by making them of higher proportion in gross government expenditure, thereby creating more jobs and enhancing the quality of public spending and the attainment of sustainable growth and development.