This article discussed the behavior of rice husk ash as fillers in polyester-fiber glass bi-panel composites to withstand the high-impact projectile impacts. This composite bi-panel consists of unsaturated polyester resin BQTN 157 and S-glass woven reinforced with rice husk ash. Specimens were prepared by varying the volume fraction of rice husk ash as fillers (3, 5, 7, and 9 %v) into the polyester resin. Composite panel manufacturing was fabricated using a hand lay-up method. Each panel has a size of 20 × 20 × 0.4 cm. Then the ballistic test was carried out using a 9 mm FN ammunition pistol with a velocity of 380 m/s projectile at a distance of 5 m. Characterizations were conducted using a Simultaneous Thermal Analyzers (STA) and a Differential Scanning Calorimeter (DSC). The optimum ballistic result is obtained on the bi-panel composites with the addition of 9 %v rice husk ash as fillers with a density of 1.604 g/cm3. This can be seen in the TGA and DSC analysis showing the changes in the panel decomposition temperature with the addition of rice husk ash. This decomposition temperature has contributed to better material characteristics. Rice husk ash increases the ability of the bi-panel composite to withstand the impact of a high-speed projectile.