The sillenite-based photocatalytic materials have attracted the researchers’ interests because of their unique crystal and electronic structures, as well as remarkable visible light absorption abilities. However, they usually have poor photocatalytic activities and stabilities owing to their structural and functional defects, such as high recombination efficiencies of photo-generated charges, low quantum yields, limited active sites, and insufficient exposure of active crystal planes. Therefore, how to achieve optimal modulation of photocatalytic activity and stability based on the structural design and functional integration of sillenite-based photocatalysts on the micro-nano scale is still a key scientific problem. This paper mainly reviews the synthesis strategies of sillenite-based micro/nanomaterials and their latest research progress in the field of photocatalysis, especially focusing on the morphology control, noble metal loading, semiconductor/graphene coupling, ion doping and the development of new sillenite-based photocatalytic systems. Moreover, the photocatalytic applications of sillenite materials are discussed. Finally, the future research prospects of such photocatalytic materials are also pointed out.