Marine filamentous fungi are ecologically important microbes renowned for their unique adaptations and metabolic versatility under challenging environments. These fungi hold substantial biotechnological significance as prolific producers of extracellular enzymes and secondary metabolites. The fungal mycelium rapidly develops biofilm over the organic substrate by enzymatically solubilizing and penetrating the surface for nutrient acquisition. Furthermore, the synthesized extracellular matrix serves as a natural binding agent, forming distinct substrate-mycelium biomass, often referred to as mycelium-based composite. In the present study, the marine fungus Aspergillus falvus JKSC-7 was explored for its ability to colonize the agro-wastes to develop a mycelium-based biocomposite (MBC) and determine its role in pyrene remediation. MBCs are sustainable and innovative functional biomaterials that utilize the metabolic ability of fungi to remove organic pollutants such as polycyclic aromatic hydrocarbons from contaminated environments. Aspergillus falvus JKSC-7 effectively colonized rice husk, wheat bran, and sugarcane bagasse, forming a biocomposite over 30 days of incubation. The scanning electron micrographs revealed a rough surface with low composite porosity, indicating dense fungal colonization. A higher dry density and low moisture retention capacity of biocomposite indicated their high stability under an aqueous environment. In addition, x-ray diffraction analysis revealed a crystalline structure with major peaks aligning with cellobiose, dextrose, and mannitol. The MBC showed 80.3 % pyrene removal efficiency over 24 h of incubation, significantly higher than the removal efficiency of routinely used polyurethane carriers. The properties of MBC render it an environment-friendly, biodegradable biomaterial for application in large-scale bioremediation processes. MBC development process integrates by-product generation with organic waste management, aligning with sustainable developmental goals and promoting a circular blue economy. Keywords: Marine filamentous fungi, Aspergillus flavus JKSC-7, Agrowastes, Biofilm-based biocomposite, Bioremediation, Blue Economy