This study aims to achieve the desired properties of green composites using a novel reinforcement strategy with lignocellulose materials, including waste pinecone powder (PCP) (Pinus hartwegii) and specially prepared short woven flax fabrics (Linum usitatissimum) (SWFs). Initially, PCP (2%, 4%, 6%, 8%, and 10%) was optimized with polypropylene (PP), and SWF was optimized by treating it with 15% of the flame retardant APP (called SWFA). The optimized PCP and SWFA were then reinforced with PP to produce the PCP-PP/SWFA composite. The effect of reinforcement on the mechanical, thermal, and flame-retardant properties of PP was studied. The mechanical test results of the PP composites with 8% PCP and 25% SWF were observed to improve significantly, by 23% and 38% respectively, compared to pure PP. The hybrid reinforcement (PCP-PP/SWFA) was observed to enhance the thermal stability of the composite by 98%, and its flame retardancy by 30%. Results obtained from the Fourier transmission infrared spectroscopy, X-ray diffraction, and scanning electron microscopy support the inference of changes in the properties of PP after performing the reinforcement. Overall, the PP properties were greatly improved compared to those reported in the literature owing to the hybrid reinforcement. Hence, we believe that this study can show the path to researchers towards high thermal applications.