This study explored the use of Rice Husk Ash (RHA) and lime as soil stabilizers for subgrade soil. RHA, a by-product of rice milling, poses environmental hazards if improperly disposed of. The optimal RHA content for subgrade stabilization is 15%, combined with 3% lime. The research found that RHA not only improves subgrade properties but also mitigates environmental pollution and offers a cost-effective stabilization method. The study evaluated engineering properties like plasticity index, maximum dry density (MDD), optimum moisture content (OMC), and California Bearing Ratio (CBR). Results showed a significant decrease in plasticity index and an increase in MDD with RHA addition up to 15%. However, further increase in RHA content led to a decrease in MDD. The combination of 15% RHA and 3% lime exhibited the highest CBR improvement (61.48%), indicating enhanced soil strength. This research suggests that RHA may be a sustainable and cost-effective subgrade stabilization material that improves pavement performance and waste utilization. RHA is abundant, easy to obtain, and economical as compared to cement as a soil stabilizer, reducing disposal issues and environmental impact.