Abstract: The Earth's surface forms the interface between the solid Earth, atmosphere, and hydrosphere, serving not only as the fundamental environment for human activities but also as a key zone where tectonic processes, climate change, and surface processes interact. Surface processes, including erosion, sedimentation, and sediment transport, not only shape topography but also influence crustal deformation and lithospheric evolution through mass redistribution, topographic loading and unloading, and thermal structure modifications. Consequently, the coupling between surface processes and deep Earth dynamics has become a major frontier in Earth system science. This review provides a systematic overview of surface process–lithosphere coupling from the perspective of quantitative numerical modeling. We first summarize the governing equations and numerical implementations of major surface processes, including fluvial incision, hillslope diffusion, sediment transport, and isostatic adjustment, and compare geomorphic models with different levels of complexity in terms of process representation, spatial scale, and computational efficiency. We then synthesize the principal feedback mechanisms through which surface processes influence the thermo-mechanical evolution of the lithosphere, including erosional unloading, sedimentary loading, stress redistribution, thermal blanketing, and sediment property variations. These mechanisms demonstrate that surface processes are not merely passive responses to tectonic forcing but can actively modify deep geodynamic processes through multiple feedback pathways. Furthermore, we review the development of coupled tectonic–surface process models and classify existing studies into four categories: landscape evolution models, geodynamic models, one-way coupled models, and two-way coupled models. By comparing their representations of feedback mechanisms, interactions between surface and deep Earth processes, and numerical coupling strategies, we highlight the evolution of the field from unidirectional forcing frameworks toward fully coupled two-way feedback systems. Recent developments indicate a transition from simplified two-dimensional approaches to three-dimensional, multi-process, and Earth system coupling. Despite substantial progress, current models remain largely based on fluvial-dominated landscape evolution frameworks. The integrated representation of sedimentary processes, glacial dynamics, weathering, impact-related processes, and their interactions remains limited, and a unified physical framework capable of consistently describing multiple feedback mechanisms is still lacking. These limitations constrain the application of coupled models to long-term Earth system evolution and to planetary environments such as Mars and other terrestrial planets. Future advances will require tighter coupling between surface processes and lithospheric dynamics within unified numerical frameworks, together with stronger constraints from multi-source observations and planetary analog studies, to improve model robustness, testability, and predictive capability. Such efforts will provide a quantitative framework into the co-evolution of surface and deep Earth systems on both Earth and planetary scales.