<p>Using agricultural biomass waste as reinforcing filler in polymer composites is of great importance in waste management and sustainable biocomposites. The main purpose of this study is to substitute chopped glass fiber (GF) with almond shell powder (ASP), thereby facilitating development of a polyester hybrid composite. Hybrid composites containing varying weight percentages (wt%) of ASP to GF (20:10, 15:15, 10:20, and 0:30) were fabricated by the compression molding method. The chemical structure of various constituents of the composites was analyzed employing FTIR spectroscopy. The tensile test results indicated that the ASP20GF10 composite (containing 20 wt% ASP and 10 wt% GF) demonstrated the maximum tensile strength of 23.1 MPa (7.9% higher than ASP0GF30 composite). The bending test revealed that the ASP10GF20 composite also exhibited commendable performance, namely 56 MPa (11.2% lower than ASP0GF30 composite). The impact strength was found to diminish with the incorporation of ASP. The microstructure of the composites was examined through SEM images, and different failure mechanisms were recognized to elucidate the corresponding mechanical properties observed. When ASP was added, there was no discernible change in water absorption, and hybrid composites performed well in this regard. The current study proved that it is possible to successfully replace a portion of synthetic glass fiber with bio-mass waste almond shell powder, exhibiting usefulness in the fabrication of fiber-reinforced biocomposites.</p> Graphical abstract <p></p>