In this study, Graphene Nano Sheets (GNS), Carbon Fiber (CF) and Hemp Fiber (HF) reinforced composites were subjected to tensile and impact tests and their characteristics were optimised using Response Surface Methodology (RSM) and Box-Behnken Design (BBD). A variety of reinforcements were included in the melted Polyethene (PE) using the mix of GNS at 0, 0.9 and 1.8% wt., CF at 0, 9 and 18% wt. and HF at 0, 9 and 18% wt. The greatest Tensile Strength (TS) of 39.84 MPa was attained by a blend of GNS (0.9% wt.), HF (18% wt.) and CF (18% wt.). The TS of the filler doped samples was 52% more than that of pure PE, due to the production of composites with optimal values of each constituent. Impact testing showed that the same optimal combination showed the highest impact strength of 131 J/m, that is 80% more than that of neat PE resin. Using the Scanning Electron Microscope analysis and Fourier-Transform Infrared Spectroscopy, it was found that the mechanical strengths of the GNS doped composites were improved due to the formation of new bonds between polymer chains and the additives.