<p>This study examines the significant interaction between geogrid encasement and cement content in determining the ultimate bearing capacity and failure modes of geogrid-encased lightly cemented stone columns (ELCSCs). It was done through comprehensive three-dimensional numerical modeling, validated by small-scale physical tests. Geogrid encasement yields proportionally greater benefits for columns with lower cement content, with the optimal encasement length varying according to column strength. Our findings indicate that, for equivalent material costs, extending the length of the thinner geogrid encasement provides superior performance compared to increasing its thickness, suggesting a practical design priority in resource-constrained applications. The results further demonstrate that the use of ELCSCs markedly improves the ultimate bearing capacity, with the bearing capacity improvement factor (BCIF) attaining a maximum value of 6.26 compared to ordinary stone columns (OSCs). Moreover, the study determines that the optimal geogrid encasement length, dependent on column strength, ranges from 2 to 8 times the column diameter. The optimal geogrid encasement length transforms the typical column head failure observed in non-encased columns to a body failure mode beneath the encasement zone. However, excessive encasement length can revert the failure mode to either column head failure or trigger soil failure, depending on the column’s inherent strength. The findings from the physical model test demonstrated a strong qualitative agreement with the preliminary numerical investigations. We developed systematic design guidelines for optimizing ELCSC performance through parametric analysis by correlating column strength with appropriate encasement length and axial stiffness based on anticipated failure mechanisms.</p>