The larvae of black soldier fly (Hermetia illucens L.) (BSFL) is an excellent decomposer for industrial and agricultural applications capable of converting low-value waste into nutritional biomass. Sesame residues is industrial food waste possess high protein and lipid content. To investigate the bioconversion process of BSFL, the larvae were raised on a low-bioburden diet consisting of sesame residue, and liquid chromatography-mass spectrometry (LC-MS) analysis was performed on the BSFL and faeces at various instars. The obtained metabolomes were subsequently evaluated through principal component analysis and orthogonal projection to latent structure-discriminant analysis to explore the differential components. Diacylglycerol was the main component of the sesame residues utilised by BSFL during metabolism. The phenylalanine, arginine, oleic acid and 10-hydroxy-8E-octadecenoic acid were identified as the major components in various instars of the BSFL metabolites. We thus concluded that BSFL have different nutritional compositions at different instar stages. Another compound with a molecular weight of 278.224 prevalent in both the larvae and faeces might play vital roles in BSFL development. The present study revealed a part of metabolic changes important in the BSFL lifecycle. Through this pioneering metabolomics profiles, the discovery of highly-valuable biomolecules on BSFL for food industrial application can be anticipated.