Accurately estimating seismically induced permanent displacement is essential for evaluating the dynamic stability of rock slopes. This study presents an enhanced model aimed at better evaluating the seismic displacement of jointed rock slopes by incorporating topographic amplification effects and the dynamic strength degradation of joints. A pseudodynamic analysis was utilized to model the amplified seismic force acting on the slope. The dynamic degradation law of the joint strength was characterized through the cyclic shear tests and integrated into the proposed model. Seismic displacement for the jointed slopes was obtained by solving the equations of motion, with sliding governed by the Mohr–Coulomb joint strength criterion. The performance of the prediction model was evaluated by comparing its results with those derived from the Newmark method and existing methods. Subsequently, the impact of amplified ground motions and joint strength degradation dependent on displacement and velocity on seismic displacement of jointed rock slopes was examined numerically. The results indicate that the proposed model can directly estimate reasonable seismic displacements of jointed slopes without explicitly specifying the yield acceleration, and it produces more conservative displacements compared to the Newmark method. Findings also emphasize that the amplified ground motion and the dynamic shear strength of joints significantly increase the seismic displacements, implying that neglecting them may lead to an underestimation of the permanent displacement of slopes. This study offers an alternative approach for estimating the permanent displacement of jointed rock slopes, which may provide valuable insights for the seismic design of slope engineering.