Cosmetics constitute an integral component of dermatological care, serving both aesthetic and protective functions. Among these, sunscreens play a critical role in safeguarding the skin against the deleterious effects of ultraviolet (UV) radiation, including erythema, photoaging, and photocarcinogenesis. Recent advancements in formulation science have led to the development of gel-based sunscreen systems, which offer distinct advantages such as non-greasy texture, improved spreadability, enhanced patient compliance, and suitability for diverse skin types. This review systematically discusses the classification and purpose of cosmetics, along with emerging trends in cosmetic science. It further elaborates on the fundamental aspects of sunscreens, including their definition, mechanism of action, and the impact of UV radiation. Special emphasis is placed on gel-based sunscreen formulations, encompassing their definition, formulation methodologies, and relevant regulatory standards, including International Organization for Standardization (ISO) guidelines and their applicability in India. Additionally, the review highlights critical quality attributes such as photostability, along with comprehensive evaluation techniques, including both in vitro and in vivo methods. The merits and limitations, packaging considerations, and practical applications of gel-based sunscreens are also examined. Overall, this article provides an in-depth and structured overview of gel-based sunscreen formulations, underscoring their growing significance in contemporary pharmaceutical and cosmetic research.