The study investigates the efficacy of geocell reinforcement in improving pavement performance by conducting full-scale instrumented model tests on both unreinforced and reinforced pavement sections under repeated loading. Geocell layers of varying heights (i.e., 75, 100, and 150 mm) were employed to assess their impact on pavement behavior. The key responses measured were stress distribution within the subgrade and rut depth. The results revealed that the reinforced pavement sections exhibited significantly lower rut depths and reduced localized stress concentrations compared to the unreinforced sections. The observed reduction in rut depth is dependent on the height of the geocell, with the 150 mm geocell providing the most substantial improvement. The presence of the geocell layer effectively anchored the encapsulated soil, enhancing the stiffness of the base layer and allowing it to act as a semi-rigid mattress. This improved load distribution reduced the stress transmitted to the subgrade, thereby minimizing permanent deformation and stress concentration. This finding underscores the potential of geocell layers to extend the service life and improve the performance of pavement sections.