The main objective of this research was to study the potential of waste polypropylene and waste wood for making wood plastic composites (WPCs). The effects of nanoclay (NC), microcrystalline cellulose (MCC), and coupling agent (MAPP) on the mechanical and thermal properties were also studied. The results showed that mechanical properties of the composites made with MCC were significantly superior to those of unfilled. Addition of MAPP could enhance the mechanical and thermal properties of the blends, due to the improvement of interface bond between the filler and matrix. The significant improvements in tensile properties of the blends composites made with MAPP and NC were further supported by SEM micrographs. The thermogravimetric analysis indicated that the addition of 5 wt% MAPP and 3 wt% NC significantly increased the thermal stability of the blends compared to the pure PP. MCC could not improve the thermal stability. The experimental results demonstrated that the waste materials used are promising alternative raw materials for making low cost WPCs.