A long-term energy nutritional imbalance fundamentally causes the development of obesity and associated fat accumulation. Lysosomes, as nutrient-sensing and lipophagy centers, critically control cellular lipid catabolism in response to nutrient deprivation. However, whether lysosome activity is directly involved in nutrient-induced fat accumulation remains unclear. In this study, worm fat accumulation was induced by 1 mM glucose or 0.02 mM palmitic acid supplementation. Along with the elevation of fat accumulation, lysosomal number and acidification were also increased, suggesting that lysosome activity might be correlated with nutrient-induced fat deposition in Caenorhabditis elegans . Furthermore, treatments with the lysosomal inhibitors chloroquine and leupeptin significantly reduced basal and nutrient-induced fat accumulation in C. elegans . The knockdown of hlh-30 , which is a critical gene in lysosomal biogenesis, also resulted in worm fat loss. Finally, the mutation of aak-2 , daf-15 , and rsks-1 showed that mTORC1 (mechanistic target of rapamycin complex-1) signaling mediated the effects of lysosomes on basal and nutrient-induced fat accumulation in C. elegans . Overall, this study reveals the previously undescribed role of lysosomes in overnutrition sensing, suggesting a new strategy for controlling body fat accumulation.