Developing advanced materials to meet the ever-growing global energy demand has accelerated research for renewable energy conversion. Perovskite materials, whether employed as active layers in solar cells or catalysts for valuable chemical conversion, have emerged as promising materials. Lead-based perovskites have achieved remarkable power conversion efficiencies and exhibit excellent optoelectronic properties. However, their intrinsic toxicity and limited long-term stability present significant obstacles to widespread commercialization. These limitations have driven an intensive research shift toward the design and synthesis of environmentally benign, lead-free perovskites (LFPs) alternatives with enhanced structural and chemical stability. This chapter comprehensively discusses the synthetic strategies, crystallographic classifications, and mechanistic insights relevant to lead-free perovskite materials. Special emphasis is placed on Sn−, Ge−, Sb−, and Bi-based perovskites, double perovskites, and mixed-metal frameworks. The classification of these materials is presented systematically based on their structural dimensionality (0D, 1D, 2D, and 3D), followed by a detailed analysis of their various synthesis methodologies, including composition, oxidation state, etc. The correlation between crystal structure, defect chemistry, and optoelectronic properties is highlighted to establish key structure–property relationships for photocatalytic applications. Finally, the chapter critically examines stability challenges, processing limitations, and scalability concerns, offering future perspectives to optimize synthetic routes and enable the development of efficient, durable, and commercially viable LFPs for various photocatalytic applications.