This research aims to provide insights into how the combination of waste plastic powder and marble powder affects the geotechnical properties of clay soil. The findings from this study can have practical implications for construction, foundation design, and environmental sustainability, as the reuse of waste materials can potentially improve soil properties and reduce environmental impacts. In this context, we executed a series of experiments involving samples that were fortified with varying proportions of plastic powder (0%, 1.5%, 2%, 2.5%, and 3%) and stabilized using marble powder at concentrations of 3%, 4.5%, 6%, and 7.5 %. The findings indicate a gradual decrease in liquid limits, swell potentials, and swelling pressure as the proportions of waste plastic powder and marble powder increase. The stress-strain curves obtained from the unconfined compressive strength (UCS) tests revealed that the incorporation of waste plastic powder into marble-stabilized soil led to an increase in UCS. These results emphasize the positive impact of waste plastic powder in enhancing the mechanical properties of the specimens. This research aims to provide insights into how the combination of waste plastic powder and marble powder affects the geotechnical properties of clay soil.