<p>This paper conducts a numerical study exploring the impact of the evolution of a weak structural plane on the overload stability and failure performance of anchored slopes. Both the macroscopic deformation failure characteristics and the internal stress–strain response of an overloaded anchored slope, following the evolution of a weak structural plane, are thoroughly presented and analyzed. As the structural plane evolves under overload conditions, it is demonstrated that the deformation mode of the slope initially evolves from a “circular damage” pattern, progressing to a combination of “circular damage and wedge damage”, ultimately resulting in “wedge damage”. Furthermore, there is a gradual shift of the stress peak and cable axial force from the top to the bottom of the slope. The formation of a stress concentration area in the anchoring zone is observed once the structural plane reaches full-length, leading to subsequent cable debonding. Moreover, it is apparent that the weak structural plane shows distinct stress differentiation, effectively isolating stress and deformation.</p>