In this paper, the pseudo-dynamic approach is used to estimate seismic passive earth thrust on retaining walls with cohesive-frictional backfills. The time-dependent pseudo-dynamic approach considers the influence of dynamic parameters such as the velocity of primary and shear waves, the period of lateral shaking, and the phase and amplitude variations of horizontal and vertical earthquake accelerations with depth. The failure plane behind the wall is assumed to be planar. The analysis is based on the equilibrium of forces which act within the failure wedge. The obtained results show that the backfill cohesion increases both the seismic passive earth thrust and the failure plane inclination angle with the horizontal plane. It is also observed that both horizontal and vertical seismic accelerations have decreasing effect on seismic passive earth thrust as well as failure plane inclination angle. The results of present pseudo-dynamic analysis propose a lower solution for seismic passive earth thrust compared to earlier pseudo-static solution available in the literature.