The study investigated the performance of Costus lateriflorus bagasse ash and cement composite for stabilization of Laterite and clay soils from Ubeta-Ula-Ubie road in Ahoada West LGA of Rivers state, Nigeria. The soil samples were prepared and tested for variations in maximum dry density (MDD), optimum moisture content (OMC), consistency limits, California bearing ratio (CBR) and unconfined compressive strength (UCS), maximum dry density (MDD), liquid limit (LL) and plasticity index (PI) of the stabilized laterite and clay soils decreased with increasing percentage of the bagasse ash composite, while optimum moisture content (OMC), plastic limit (PL) and unconfined compressive strength (UCS) were increased with the proportion of bagasse ash. This study establishes that an appropriate proportion of bagasse ash content in soil stabilization would enhance the properties of soil suitable for pavement and road construction. Comparatively, bagasse ash performed better in Laterite soil than clay soil at optimum proportion of 0.75% and 7.5% cement composition.