<p>The main objective of this study is to experimentally investigate the potential use of marble stone waste as a stabilizing material to improve the geotechnical performance of mine haul road pavements. Geotechnical testing including Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR), and triaxial tests, along with microstructural analyses using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDAX), and Fourier transform infrared spectroscopy (FTIR), was carried out on natural soil and samples stabilized with 0–30% marble powder (MP) in 5% increments. Furthermore, hydrated lime was added to the marble powder–clay mixtures to enhance pozzolanic reactions and further improve the soil mechanical behavior. The experimental results were then complemented by a 3D finite element analysis using the hardening soil (HS) model to evaluate the stress–strain response of the haul road pavement and assess the overall stabilized soil performance. The results demonstrated that adding marble powder significantly improved the geotechnical properties of the soil, evident in the liquid limit and plasticity index, along with an increase in its bearing capacity. Adding a small amount of hydrated lime (2%) further enhanced the soil’s characteristics by promoting the pozzolanic reactivity of the binder. Based on the CBR results, a mixture containing 25% marble powder and 2% hydrated lime was identified as the optimum composition, showing promising performance with respect to base course requirements under the investigated conditions. Numerical analysis using the hardening soil model confirmed that the stabilized layers exhibited strain levels below the critical limit of 2000 micro-strains when appropriate layer thickness was considered. These findings show that the combination of marble powder and lime is a viable technical method to improve the structural performance of mine haul roads.</p>