<p>Rock masses containing pre-existing damage are more susceptible to time-dependent deformation and failure under long-term loading. To better understand the nonlinear time-dependent deformation characteristics of fractured rock with pre-existing (initial) damage, a damage evolution model that considers the combined effects of initial macro- and mesoscopic damage is proposed. Based on this, a novel nonlinear creep damage model for fractured rock has been developed. This model accounts for the influence of initial damage on creep deformation and effectively captures the decelerating–accelerating characteristics of brittle creep in fractured rock. Subsequently, the effects of initial macroscopic damage on the creep damage behavior of sandstone were analyzed through uniaxial compression and stress-stepping creep loading tests on sandstone specimens with macroscopic fractures at various inclinations. The relationship between initial macroscopic damage and the long-term strength was also investigated. Finally, the proposed model was evaluated against laboratory creep data of fractured rock with different initial macro- and mesoscopic damage levels, demonstrating its good applicability. Overall, this study establishes a combined analysis framework for creep damage that incorporates both initial macro- and mesoscopic damage, and provides a new approach for long-term performance evaluation of geotechnical engineering in complex environments.</p>