This study investigates the fabrication process of biocomposites and their resultant mechanical and thermal properties, essential for evaluating the performance of finished products. Polypropylene random copolymer (PPRC) was employed as the matrix phase, while rice husk (RH), a biowaste filler, was incorporated in varying concentrations. The rice husk fiber was treated with alkali (RHT) to enhance its lignocellulosic content. To improve interfacial bonding, maleic anhydride and NaOH treatment were utilized. Glass fiber grafted on polypropylene (PPGF) and talc powder functioned as additives. Both raw and treated rice husk fibers were characterized using Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and analytical methods to quantify the composition of lignin, cellulose, hemicellulose, and ash. Significant structural changes were observed, with cellulose content increasing from 26% to 53%. Wood polymer composites (WPC) produced from raw and treated rice husk were evaluated based on morphological studies, Izod impact testing, water absorption, heat distortion temperature (HDT), and VICAT softening temperature (VST). The results demonstrated that the HDT and VST of WPC improved by 24% and 7%, respectively, compared to PPRC, indicating enhanced structural and thermal properties. Additionally, impact strength and water absorption were found to be dependent on cellulose concentrations in the biocomposite. This study underscores the environmental benefits of utilizing biowaste rice husk in biocomposites, promoting sustainability by converting agricultural waste into valuable materials with enhanced properties for various industrial applications.