The effective utilization of rice husk ash (RHA) as an asphalt modifier promotes agro-waste valorization and enhances flexible pavement performance. This study aimed to investigate the impact of blending methodology on the characteristics of RHA–modified asphalt (RHMA) and to optimize the blending parameters using response surface methodology (RSM) to achieve a homogenous and storage-stable RHMA. A novel multi-level optimization framework was developed that simultaneously evaluates the influence of multiple blending parameters. Sixty RHMA samples were laboratory-prepared using low- and high-viscosity graded asphalt and comprehensively evaluated. This research work revealed that innate properties of base asphalt and the blending parameter combinations significantly influenced the performance of RHMA. Though higher levels of blending parameters enhanced RHMA stiffness, RHA dosage has detrimental effect on storage stability. Using RSM, the optimum RHA dosage, blending duration, blending temperature, and shear rate were determined for V1RHMA and V3RHMA. The optimal parameters were 15.5 %, 79 min, 150°C, and 1,435 rpm for V1RHMA, and 13.4 %, 86 min, 150°C, and 1,025 rpm for V3RHMA. The optimized blending parameters were experimentally validated, and the statistical indicators underscored the high reliability. Overall, this research highlights the crucial role of blending parameter optimization in enhancing the characteristics of RHMA.