The study investigates the long-term relationship and dynamic short-term impact of public debt on foreign private investment for a developing country – Nigeria during the period 1962 to 2012. The paper deploys cointegration model to examine long-term relationship between the variables. The study also examines dynamic short-term impact and causality between public debt and foreign private investment using the VECM and Granger causality test. The study further examines the response paths of foreign private investment variable due to public debts shocks using variance decomposition. The results confirm absence of long-term relationship between public debt and foreign private investment in Nigeria. The results also show that external debt has negative impact on foreign private investment in the short-term. Finally, the results show that there is no causality between foreign private investment and public debt. The major economic implication of these findings is for debt management authorities to be conscious of growing external debts as it discourages foreign private investments into Nigeria.