The reuse of waste emerged as a critical response to challenges posed by the rapid demand growth in civil life. The need to conserve resources, reduce waste disposal, and promote sustainability has been sought after as an appropriate substitute for methods utilizing traditional materials in infrastructure. Agricultural wastes have been sought after for their application in various sectors, addressing both environmental concerns and resource optimization, highlighting the importance of innovative waste management strategies. One such material, cow dung waste, has significant potential in not only addressing waste management issues but also contributing to ecologically conscious practices. This paper aims to utilize finite element analysis for investigating subgrade stabilization using 10% cow dung ash and compare its deformation parameters against natural (unstabilized) soil subgrade for a traffic speed of 50 msa and a vehicle speed of 20 and 60 kmph. Desirable outputs have been taken from laboratory tests, which include determination of Atterberg Limits, Standard Proctor Test, California Bearing Ratio Test, and Unconfined Compression Test for soil treated with 10% ash and natural soil. The thicknesses of pavement layers have been estimated with reference to IRC 37:2018 and validated using IITPAVE software. Untreated soil has a total pavement thickness that is 240 mm thicker than treated soil. Using PLAXIS 3D, the pavement deformation has been computed for a 50-m segment of a two-lane road. The analysis’s findings at the targeted nodes show that the unstabilized subgrade deforms more than the stabilized subgrade by about 60%.