Hydrogels are a remarkable class of materials meticulously engineered for biocompatibility, making them the cornerstone of soft contact lens technology. Their hydrophilic nature allows them to retain water, effectively replicating the eye’s natural hydration and the cornea’s high-water content. With inherent optical clarity, flexibility, and oxygen permeability, hydrogels address the complex demands of ocular applications, providing both comfort and optimal eye health. This chapter delves into the unique features that make hydrogels ideal for contact lenses, beginning with a detailed exploration of their fundamental properties and their role in mimicking the eye’s natural environment. It emphasizes the critical importance of tailoring hydrogels to meet specific ocular needs, such as achieving an optimal balance of hydration, oxygen permeability, and biocompatibility. The chapter further discusses the synthesis of hydrogels, including the selection and combination of monomers, crosslinkers, and initiators, which are meticulously engineered to form the three-dimensional networks that define hydrogel functionality. Additionally, the chapter highlights the ways in which hydrogels have been optimized for advanced performance, from enhancing optical properties to improving mechanical durability. Finally, it examines the transformative impact of hydrogels on the evolution of contact lens technology, showcasing their role in enabling extended wear lenses and driving innovations such as drug delivery and smart contact lenses. Through these advancements, hydrogels continue to redefine the possibilities of vision correction and ocular health.