This study investigated the impact of public debt on the Nigerian economy from 1987 to 2020. The specific objectives were to determine the impact of external debt on economic growth and to examine the impact of domestic debt on economic growth in Nigeria. The ex-post facto research design was adopted to enable the researcher make use of secondary data to determine the cause effect relationship of public debt on economic growth in Nigeria. The dependent and independent variables were observed over the period, 1987 to 2020. Empirical investigation was carried out on the basis of time series data collected from the Central Bank of Nigeria Statistical Bulletin. The unit root test performed on each of the variables in the model using the Augmented Dickey-Fuller (ADF) unit root tests showed that the variables were stationarity at level and data analyzed with Ordinary Least Square. (OLS). Findings from this study revealed that external debt impacted negatively on economic growth of Nigeria while domestic debt impacted positively on economic growth of Nigeria. Following these findings, this study recommended that policy makers should discourage external borrowing by all means and encourage domestic borrowing, while integrating appropriate measures to ensure efficient management of domestic debts