Abstract: Tin(IV) oxide (Sn₃O₄) is layered tin and exhibits mixed valence states. It has emerged as a highly promising visible-light photocatalyst, attracting considerable attention. This comprehensive review is aimed at providing a detailed overview of the latest advancements in research, applications, advantages, and challenges associated with Sn₃O₄ photocatalytic nanomaterials. The fundamental concepts and principles of Sn₃O₄ are introduced. Sn₃O₄ possesses a unique crystal structure and optoelectronic properties that allow it to absorb visible light efficiently and generate photoexcited charge carriers that drive photocatalytic reactions. Subsequently, strategies for the control and improved performance of Sn₃O₄ photocatalytic nanomaterials are discussed. Morphology control, ion doping, and heterostructure construction are widely employed in the optimization of the photocatalytic performance of Sn₃O₄ materials. The effective implementation of these strategies improves the photocatalytic activity and stability of Sn₃O₄ nanomaterials. Furthermore, the review explores the diverse applications of Sn₃O₄ photocatalytic nanomaterials in various fields, such as photocatalytic degradation, photocatalytic hydrogen production, photocatalytic reduction of carbon dioxide, solar cells, photocatalytic sterilization, and optoelectronic sensors. The discussion focuses on the potential of Sn₃O₄-based nanomaterials in these applications, highlighting their unique attributes and functionalities. Finally, the review provides an outlook on the future development directions in the field and offers guidance for the exploration and development of novel and efficient Sn₃O₄-based nanomaterials. Through the identification of emerging research areas and potential avenues for improvement, this review aims to stimulate further advancements in Sn₃O₄-based photocatalysis and facilitate the translation of this promising technology into practical applications.