In recent years, research has shifted away from conventional materials and alloys to composite materials to create lighter, more efficient materials for specific applications. In order to generate lighter, more efficient materials for specific purposes, research has migrated away from traditional materials and alloys and toward composite materials in current years. Blended microbially nanocomposite that takes advantage of organic flax fibres and nanoreinforced biobased polymers can increase characteristics while keeping the environment in mind. Adding aluminium trihydride (ATH) powder to the natural resin allows it to sustain rigidity without compromising toughness while increasing barrier and mechanical characteristics. Investigation of several composite samples confirmed this positive effect, with systems that contain 10% epoxidized methyl soyate (EMS) and 2.5 wt.% ATH maintains the original resin’s rigidity, strain to fracture, and hygromechanical characteristics while enhancing toughness. Mechanical testing like interlaminar shear strength (ILSS) was found per the standard ASTM testing method. Among the various combinations, the second combinations (77.5 wt.% polyester, 2.5 wt.% ATH, and 20 wt.% of flax fibre) provide the highest value of ILSS (34.31 MPa). Scanning electron microscopy was used to examine the fractured surface of the nanocomposites and the degree of dispersion of the ATH filler.