In this study, we analyzed the effects of cadmium (1.25, 2.5, 5, 10, 20, and 40 mg per 100 g of nutrient) on total protein, lipid, and glycogen levels, lipid peroxidation (MDA), superoxide dismutase (SOD) and catalase (CAT) activities, and metal accumulation in Galleria mellonella L. High concentrations of Cd (20 and 40 mg) significantly lowered total protein, lipid, and glycogen levels. MDA level significantly increased when the nutrient contained 5 mg and more of Cd, whereas SOD activity significantly increased at Cd concentrations starting from 1.25 mg. CAT activity significantly decreased at all concentrations. Metal accumulation also significantly increased in a dose-dependent manner. These changes observed on activity of antioxidant enzymes, energy reserves, MDA content, and accumulation levels of Cd can be used as a reliable biomarker of environmental heavy metal pollution in model insect G. mellonella.