Abstract: polypropylene (pp) based hybrid composites with treated hollow glass microspheres (t-hgm) as inorganic low-density filler and naturally sourced bamboo fibers for strength reinforcement are prepared. the hybrid composites may fulfil the need for potential lightweight and high-strength modern engineered materials required for automotive and aerospace industry applications. the interfacial adhesion between different filler-matrix interfaces such as fiber-pp and t-hgm-pp has been enhanced by using maleic anhydride-grafted polypropylene (ma-g-pp). pp and ma-g-pp taken in a 9:1 ratio constitute the base matrix (bm), while the bamboo fiber is varied from 0 to 20 wt% keeping the hgm loading fixed at 10 wt% with respect to bm. while a density reduction of ~8.5% is achieved by the addition of hgm's, the decrease in mechanical strength has been more than compensated by the added bamboo fibers. interestingly, for 20 wt% fiber addition the tensile, flexural and impact strengths increased by 23.5%, 38.5% and 47.9%, respectively, over and above the virgin pp values. the morphological studies via sem showed good wetting of both fillers without any signs of aggregation and hindrance to each other's property contribution. the work paves the way for engineering and design of components based on another promising light-weight high-strength natural fiber based composites. summary and conclusion treated hollow glass microspheres and short bamboo fiber based pp composites have been prepared and investigated in this study for their mechanical properties and morphology. while the use of sbf improved the mechanical properties of virgin pp significantly, hgms controlled the increase in density due to sbf addition. for example, the tensile strength of virgin pp has been found to increase by a maximum 18.39% and tensile modulus by 73.25% for a 20% sbf addition. likewise, the improvement in flexural strength and modulus has been 38.51% and 73.98% respectively, while the impact improved considerably by 47.92%. the enhancement in mechanical properties is attributed to the addition of high modulus sbf and also due to the good interfacial adhesion due to the pre-treatment of sbf and hgms. the morphological studies further provide evidence to this interfacial wetting and good dispersion of t-hgms and sbf in the matrix. the composites are proposed as suitable for use in industrial applications such as in automotive parts for replacing pp with enhanced strength and relatively environment-friendly materials with similar or reduced density.