<p>The seismic stability analysis of geosynthetically reinforced soil walls, which considered shear and moment as well as tensile resistance for inextensible sheet reinforcement, was a novel topic for which only scarce studies were found in the literature. This study employed an analytical approach to investigate the internal stability of reinforced soil walls under mobilized transverse force. It considered the realistic non-linear response of the cohesive frictional backfill and employed the pseudo-static method through the application of limit equilibrium theory. The findings were illustrated in terms of the safety factors due to the transverse displacement of inextensible sheet reinforcement. The normal stress–displacement response due to transverse force or displacement was evaluated for non-linear responses of the backfill, assuming complete mobilization of shear resistance at the soil reinforcement contact surface. Parametric analyses were performed to evaluate the impact of safety factors, shear strength parameters, surcharge, interface friction angle, length of reinforcement, and number of reinforcement layers under seismic conditions.</p>