This current study investigates the effect of 0%, 5%, and 10 wt % ophiopogon japonicus ash (OJA) incorporation of fillers, with and without alkali-treated jute fiber on the mechanical characteristics like compressive, tensile, impact strength, and flexural strength of Jute fiber reinforced with epoxy-based composite. Commonly, Jute Fiber is treated with alkali treatment to enhance fiber matrix interface binding, increase surface roughness, and remove impurities. By hand layup process, the six composite samples were developed by incorporation of different compositions of fillers. The results found that extreme tensile strength achieved for treated composite with 10% OJA filler is 60 N/mm2, a 20% improvement over the 5% OJA filler concentration on treated composite. Similarly, the compressive strength reached 82 N/mm2 for the treated composites, which is 17% higher than that of the untreated composites. These results evidenced that proper fiber treatment and optimized filler content enhance the mechanical properties and make them promising for lightweight applications in sustainable engineering.