The aim of most government when accumulating public debt is to enhance an improved economy. However, economic performance has been abysmally poor in Nigeria despite its high debt profile. Few studies have considered the non linear relationship between public debt and economic performance in Nigeria using the threshold cointegration technique. Therefore, this study examined the threshold effect of public debt on economic growth using time series data from 1985 to 2020. Findings revealed asymmetric cointegration between public debt and economic growth (F[p1 = p2 = 0], = 13.118, p ˂ 0.05). The results of the asymmetric error correction model found that public investment had a positive and significant relationship with economic growth (β = 0.675, t = 3.542, p ˂ 0.05) while trade openness had a negative and significant relationship with economic growth (β = -0.226, t = -3.617, p ˂ 0.05).The study concluded that there is a threshold cointegrating relationship between public debt and economic growth in Nigeria. Therefore, the study recommends that the Nigerian government should efficiently utilize funds borrowed domestically and 
contract less of external debt in order to maintain a sustainable economic growth. 

Keywords: Domestic Debt, External debt, Public Debt, Economic Growth, Threshold Cointegration, Nigeria.