Economic complexity reflects the accumulation of collective knowledge and the productive capabilities of an economy. This study investigates the short- and long-run effects of energy subsidies and energy efficiency on economic complexity in eight selected OPEC member countries over the period 2000–2023. The dynamic relationships among the variables are estimated using the Panel ARDL model and the Pooled Mean Group (PMG) estimator. In addition, a country-specific Economic Policy Uncertainty (EPU) index is constructed using Principal Component Analysis (PCA) based on monetary and fiscal policy indicators, while oil price volatility is estimated using an EGARCH model; both measures are incorporated into the empirical model. The findings show that energy subsidies have a positive and statistically significant effect on economic complexity in the short run (0.88), but a negative and statistically significant effect in the long run (−0.57). Energy efficiency has a positive and statistically significant effect in both the short run (0.59) and the long run (0.29). Moreover, oil price volatility (−0.58) and economic policy uncertainty (−0.07) have negative and statistically significant long-run effects on economic complexity. The negative and statistically significant error-correction coefficient (−0.34) indicates that approximately 34% of short-run disequilibrium is adjusted toward the long-run equilibrium relationship in each period. The findings underscore the importance of improving energy efficiency, developing technology, diversifying production structures, and reducing oil-dependent economies’ reliance on subsidized energy and oil revenues.