This study investigated the relationship between trade economics and sustainable economic development in Nigeria using annual time series data from 1996 to 2025. The analysis employed the autoregressive distributed lag (ARDL) bounds testing approach to examine both short-run dynamics and long-run equilibrium relationships among GDP per capita (LGDPPC), trade openness (LTOP), terms of trade (LTOT), trade balance (TRB), exchange rate (LEXC), and inflation rate (LINF). The empirical results confirmed the existence of a stable long-run cointegrating relationship among the variables, as validated by the F-Bounds test statistic of 6.66, which exceeds the upper critical bound at the 5 per cent significance level. The model demonstrated excellent fit (R² = 0.9914), passed all diagnostic tests (normality, serial correlation, and parameter stability via CUSUM of Squares), and remains robust across major economic shocks. The study concluded that the gains from trade serve as a significant engine of sustainable economic development in Nigeria, but its benefits are conditional on trade quality and structural transformation rather than mere volume. These findings underscored the need for export diversification, value addition, and macroeconomic stability to maximise the developmental gains from trade integration.