Black soldier fly (BSF) larvae (Hermetia illucens L.) are recognized as effective agents for the bioconversion of organic waste, including agricultural residues. The bioconversion efficiency of BSF larvae is highly dependent on the substrate and is considerably reduced when the substrate is rich in cellulose. Palm kernel cake (PKC), a by-product of palm oil processing with considerable potential for upcycling, contains high levels of lignocellulose. Its lignin content can impede nutrient release, making pretreatment essential before its use as a feed substrate. This study evaluated the growth and developmental performance of BSF larvae reared on PKC subjected to biological pretreatment with Rhizopus oligosporus (RO), Phanerochaete chrysosporium (PC), and Aspergillus niger (AN), in combination with a total feeding system (TFS) where feed was provided only once at the start of rearing. Fungi were cultured on PKC for 10 days before being fed to six-day-old BSF larvae; non-fermented PKC and commercial chicken feed served as controls. Larval performance was assessed by measuring dimensional growth (length and weight) and survival rate (SR) across five replicates per treatment. All treatments exhibited high survival rates (85.3 ± 3.02-91.4 ± 5.69%), with the highest values observed in the positive control (91.4 ± 5.69%) and the AN treatment (91.4 ± 3.25%), and the lowest in the negative control (85.3 ± 3.02%). Among the fermented treatments, AN resulted in the highest larval growth rate (6.42 ± 0.28 mg/larva/day), which was significantly higher than that of the non-fermented negative control (4.81 ± 0.21 mg/larva/day) (p < 0.05). These results suggest that PKC pretreatment via A. niger fermentation is a suitable strategy for improving PKC quality as a feed substrate for BSF larvae.