Abstract: Computational geodynamics is an interdisciplinary frontier discipline integrating geodynamics and computational science. Relying on high-performance numerical computation, it endeavors to uncover the mechanisms behind multi-scale, cross-sphere, and complex dynamic processes inside the Earth and terrestrial planets, and has become an indispensable research method in this field. This paper comprehensively reviews the theoretical foundations and core numerical methods of computational geodynamics, and focuses on its key roles and advances in the research of geodynamic processes within the Earth and internal processes of terrestrial planets. In terms of geodynamics within the Earth, data assimilation techniques enable the reconstruction of four-dimensional mantle evolutionary sequences consistent with plate tectonic history and geological and geophysical observations; refined modeling of more realistic physical processes is gradually uncovering the deep-seated mechanisms underlying the formation, maintenance of plate boundaries and earthquake occurrence; cross-lithospheric coupling models have facilitated a systematic understanding of the complex interactions among various components of the Earth system; by applying the same set of physical laws to the early Earth, terrestrial planets and even exoplanetary super-Earths, we are gaining insights into the unique conditions required for the formation and evolution of the habitability of Earth—the only known cradle of life—within a more universal context. Finally, the paper prospects the future development trends in this discipline, covering the joint constraint of multiple observations and dynamic self-consistency in data assimilation, the testability of complex physical processes, algorithm innovation for long-term multi-scale high-resolution simulations, as well as the development of inversion methods. This paper aims to demonstrate that Computational Geodynamics, with its unique advantage as a numerical laboratory, is advancing the understanding of Earth and planetary interior processes toward a more quantitative, self-consistent, and systematic integration driven by multi-physics coupling and multi-source data.