Water splitting is an essential process for producing the cleanest nonrenewable energy source, hydrogen. Water is a precious and abundantly available natural resource. The effective generation of hydrogen from water poses one of the major challenges in the current energy crisis. To satisfy future energy requirements, large-scale hydrogen production requires alterations to existing materials and methods. In this regard, natural water splitting via photosynthesis stands out as an optimal solution. The utilization of nanomaterials in hydrogen production through water splitting is among the most promising strategies. Nanomaterials serve as the most efficient means of generating hydrogen through photocatalytic water splitting in a more straightforward, cost-effective, and sustainable way. In this chapter, we present an overview of the effectiveness of various photochemical water splitting techniques aimed at producing renewable hydrogen energy, with a specific emphasis on natural water splitting through photosynthesis. We also investigate the application of different metallic and nonmetallic nanomaterials in anthropogenic or artificial water splitting methods. Furthermore, we explore various characteristics of nanomaterials that can improve hydrogen production. In this chapter, we delve into the fundamental principles of natural water splitting through photosynthesis, artificial photosynthesis, and photolytic water splitting, the function of nanomaterials in water splitting, their role in natural photosynthesis, and the future potential of hydrogen as an alternative energy source.