[Aim]  To clarify the effect of exogenous melatonin on the supercooling and freezing points of Spodoptera frugiperda. [Methods]  Using the food-mediated method, the 1st-6th instar of fall armyworm(S. frugiperda) larvae were fed an artificial diet containing different concentrations (0, 0.2, 2, 20, and 200 µg/g) of exogenous melatonin after which their supercooling and freezing points were measured and compared. [Results]  Ingesting exogenous melatonin significantly reduced the supercooling and freezing points of 3rd to 6th stage larvae, pupae and adults, compared to the control, indicating that exogenous melatonin enhances the cold resistance of S. frugiperda. Increasing the exogenous melatonin concentration significantly lowered the subcooling and freezing points of each age class relative to the control group (P < 0.05). The lowest subcooling and freezing points for each age class were measured at an exogenous melatonin concentration of 200 µg/g.The males of S. frugiperda exhibited slightly higher supercooling points and freezing points than females. [Conclusion]  Exogenous melatonin can lower the supercooling and freezing points of S. frugiperda, thereby enhancing its cold hardiness.