Hermetia illucens is a very promising insect due to its ability to convert low-value substrates in highly nutrient feed. Its feeding and nutrition are important issues. This work aimed to study the effect of different substrates composed of coffee silverskin, by-product of the roasting process, enriched with different inclusion of microalgae (5%, 10%, 20%, 25%), Schizochytrium limacinum and Isochrysis galbana, coupled with the assessment of environmental sustainability by LCA. In general, the inclusion of microalgae caused an increase in the growth performance of the larvae, although S. limacinum showed the best results. Higher prepupal weight were observed in larvae fed on 20% and 25% of S. limacinum, shorter development times in larvae fed on 25% of both S. limacinum and I. galbana and higher growth rate were observed in larvae fed on 25% of S. limacinum. Anyway, the inclusion of 10% of S. limacinum showed a small difference with the higher inclusions. Moreover, the 10% of S. limacinum achieved the best waste reduction index. Therefore, considering the greater inclusion of microalgae, the higher the environmental impact of larvae production, the addition of 10% of S. limacinum seems to be the best compromise for the larval rearing.