As space remote sensing technology continuously evolves toward large apertures and high resolutions, optical systems impose increasingly stringent requirements on the mass, specific stiffness, and surface figure stability of mirrors. Leveraging unparalleled design freedom, additive manufacturing (AM) technology enables the physical fabrication of complex architectures—such as topology optimization (TO), lattices, and Voronoi structures—thereby breaking through the limitations of traditional lightweight mirror designs. This review first introduces the relevant manufacturing technologies for AM space mirrors and analyzes the characteristics of metallic and ceramic materials suitable for AM, with a particular focus on the advantages and limitations of the two most widely applied core materials: AlSi10Mg and silicon carbide (SiC). Subsequently, it reviews the state of the art in AM space mirrors, organized according to their structural typologies. Furthermore, it delves into the critical post-processing technologies required to achieve high-precision surface figures and summarizes the prevailing challenges confronting AM mirrors. Finally, it outlines future research directions for AM mirrors.