The presence of a reinforcement layer below a rigid footing always improves the load–settlement behavior of the footing. In the present study, the load–settlement behavior of a circular footing resting on unreinforced and geocell-reinforced pond ash bed is investigated using a finite-element software package (PLAXIS 3D). The geocell mattress within the pond ash bed is modeled by considering the actual geometry of the geocell using AutoCAD software. The effects of various parameters like depth of placement of geocell layer, width of geocell reinforcement, and height of reinforcing layer on the ultimate bearing capacity value of circular footing resting on pond ash bed have been observed. The optimum depth of placement of geocell layer and width of geocell layer have been reported in this study. It is observed that, due to geocell reinforcement, the load–settlement behavior of the circular footing has improved significantly, which proves the applicability of geocell-reinforced pond ash as a sustainable foundation material. Due to geocell reinforcement, the ultimate bearing capacity of the circular footing resting on pond ash bed increases about 36.14%–134.42% as compared to unreinforced pond ash bed.