The main objective of the present research is to study the effect of using confining system to improve the bearing capacity of the supporting soil. The effects of increasing subgrade stiffness using confining walls on the foundation subgrade and the structure stability are investigated. This practice is investigated numerically using three-dimensional finite element analysis (Plaxis3D). A square foundation subjected to uniform applied stress is idealized with and without confining walls. Based on the results of the numerical analysis, charts are used to evaluate the enhanced bearing capacity of square foundations resting on extended sand, sand relative density, rigid confining walls depth, maximum deformation of the foundation. Moreover, it was observed, for the study variables considered that the bearing capacity can be improved to 3.8 times by laterally confining the soil subgrade. The level of improvement is directly proportional with confining wall depth to foundation width ratio and reversely proportional with sand relative density. However, the capacity is less sensitive to the foundation embedment depth.