The current study employs the finite element (FE) software PLAXIS 3D to investigate the behavior of a soft subgrade with the use of a geocell layer. The Mohr–Coulomb constitutive model is utilized to represent the subgrade and base soil behavior in the FE analysis, while the linear elastic model simulates the behavior of the geocell. To validate the FE analysis, the numerical outcomes are compared with experimental data from previous literature. Additionally, the validated numerical model is used to investigate the impact of various infill materials and geocell placements at different locations on the overall performance enhancement of the pavement. The research outcomes are evaluated based on the pressure-settlement response, revealing that the higher density of the infill material leads to a pressure response increase ranging from 9 to 19% when compared to the pressure responses exhibited by other types of infill materials for both geocell and planer-reinforced pavement. The study also shows that the geocell reinforcement enhances the load-bearing capacity of the soil layer by approximately 15% compared to the planar reinforcement.