In cases where the soil underlying the foundation is loose and unable to carry the loads imposed by the structure, improving the soil by an appropriate approach is essential. The application of polymeric materials such as geogrids, in recent decades, has been of interest to engineers and researchers in order to increase the bearing capacity of soil foundations. Geogrid reinforcements allow for achieving an increased bearing capacity or a reduced layer thickness of soil improvements. The most significant factor used in the design of shallow foundations is the bearing capacity of the foundation along with its settlement. In geotechnical investigations, probabilistic analyses could be beneficial in the relevant problems. The Monte Carlo probabilistic simulation method is one of the most commonly used methods in solving geotechnical problems. Therefore, in the current research, a reasonable estimation of the bearing capacity of a strip foundation has been conducted by using a numerical model with the help of the discrete-element software FLAC3D in conjunction with the calculation of the probabilistic bearing capacity via the Monte Carlo simulation method and by considering the uncertainty of the soil internal friction angle and cohesion coefficients.