The study investigates the strength improvement of kaolinite clay soil with the inclusion of various percentages and combinations of silica fume (SF), eggshell ash (ESA) and lime (L). Hence, the mechanical characteristics of various mix ratios of SF, ESA, and L are examined through the standard Proctor, unconfined compressive strength (UCS), and consolidated isotropic undrained (CIU) triaxial tests. The samples were treated for 1, 7, 14 and 30 days and examined under the UCS and CIU tests. The experimental results show that the strength of the kaolinite clay significantly rises with the inclusion of SF, ESA, and L at dissimilar mix ratios and curing days. The Field Emission Scanning Electron Microscopy profile has illustrated that the kaolinite clay soil molecules were fused jointly with SF, ESA, and L to form calcium aluminate hydrates (CAH) and calcium silicate hydrate (CSH), which enhanced the development of strength of the stabilized kaolinite clay. The mixture of SF, ESA, and L resulted in a significant strength increment of the kaolinite clay soil up to 88.74%. By stabilizing expansive clays effectively, the resulting improvement in soil strength and reduction in swell-shrink behavior can significantly enhance the durability and lifespan of foundations, pavements, and other geotechnical structures.