The increasing volume of agricultural biomass waste presents both an environmental challenge and an opportunity for sustainable resource recovery. Traditional waste management methods can be costly and inefficient, making biological recycling approaches such as vermicomposting and insect composting viable alternatives. This chapter explores the low-cost recycling of agricultural biomass into nutrient-rich compost using Black Soldier Fly (BSF) larvae and compost worms. These bioconversion processes offer an eco-friendly solution for organic waste treatment while enhancing soil health and fertility. Vermicomposting facilitates microbial enrichment, including phosphate-solubilizing bacteria and nitrogen-fixing microbes, which improve nutrient availability in compost. Similarly, BSF larvae efficiently degrade organic residues while reducing heavy metal accumulation, producing compost with enhanced agronomic value. The chapter also examines the influence of feedstock composition, earthworm species, and microbial diversity on nutrient dynamics and metal sequestration during composting. Additionally, it highlights the potential applications of BSF-derived compost in sustainable agriculture.