High swelling clay soil-related issues result in financial burden for property owners when compared to the combined economic effect of earthquakes, floods, hurricanes, and tornadoes. These soils are always a challenge for civil and geotechnical engineers. Clay soils with montmorillonite mineral can pose a significant hazard to engineering constructions such as buildings, roads, canal linings etc., due to their capacity to shirk and swell with alteration in the water content. Though numerous studies are carried out on swelling soils by researchers, still in the light of utilization of plastic waste, a study is conducted in the laboratory to bring out the effect of plastic waste on unconfined compression strength (UCS), California bearing ratio (CBR) and swelling behavior of fly ash stabilized clay soil. Clay soil tested in the laboratory possesses free swell index of 100%, liquid limit of 54% and % fine fraction (silt & clay) 68. The fly ash proportions used in the study are 0, 2, 4, 6, 8 and 10%. The plastic waste made into pieces was added to the fly ash stabilized clay in the proportions of 0, 0.05 and 0.1 by dry weight of soil. From the results, it is found that the effect of plastic waste on UCS and CBR is not significant but, the free swell index has reduced from 100 to 30%.