The soil has many engineering properties in its natural state. These properties, however, can be altered to meet desired standards by combining the soil with certain materials. The combined effect of rice husk ash (RHA) and sawdust ash (SDA) on the index and strength properties of expansive soil is investigated in this study. Expansive soil samples were collected in Addis Zemen town for laboratory testing. Rice husk is an agricultural byproduct produced by rice milling. Sawdust is a byproduct of wood cutting and grinding. Compaction, California bearing ratio, unconfined compressive strength, Atterberg limit, specific gravity, shrinkage limit, and free swell are among the properties that have been evaluated. Rice husk ash content of 4%, 7%, or 10%, depending on the weight of the dry soil. The proportions of sawdust ash added to the soil are 1%, 3%, and 5%. The experimental mixes revealed that the expansive soil treated with 10% rice husk ash was further stabilized with 3% sawdust ash, yielding better results. Natural soil index properties confirmed that it belongs to CH in the USCS classification system. This type of soil provides little engineering benefit. The addition of RHA and SDA to natural soil reduced the liquid limit, plasticity index, maximum dry density, and free swell properties while increasing the OMC, UCS, and CBR, according to laboratory results. Keywords: Expansive soil, Rice husk ash, Sawdust ash, Stabilization