Nanophotocatalysts are a significant achievement in material science, offering remarkable potential for environmental remediation, energy conversion, and organic synthesis. Materials of this kind take the advantages of the unique features of nanostructures to augment photocatalytic efficiency, addressing limitations of traditional bulk catalysts. Nanophotocatalysts are introduced and classified as a diverse spectrum of materials, which inter alia include: metal nitrides, oxides, sulfides, and hybrid composites, each with distinct mechanisms and applications. The chapter explores the fundamental principles underlying the design and synthesis of nanophotocatalysts, emphasizing their structural and electronic characteristics that drive catalytic activity. It delves into various classification schemes based on composition, morphology, and functionalization, providing a thorough overview of the most recent advances in the area. Advanced characterization techniques and methodologies for assessing photocatalytic performance are discussed, highlighting the importance of nanostructure engineering in optimizing efficiency. The chapter further addresses the emerging trends and future directions in nanophotocatalyst research, such as incorporation of artificial intelligence and machine learning into catalyst design and development of sustainable and scalable manufacturing processes. This ultimately aims to leverage nanophotocatalysts for innovative solutions to global challenges.