Kojic acid is a natural organic compound that was first isolated from Saccharomyces cerevisiae by Japanese scholars. Due to its strong ability to inhibit tyrosinase activity and reduce melanin synthesis, it exhibits excellent whitening effects. In recent years, with the increasing demand for functional ingredients in the cosmetics industry, kojic acid and its derivatives, as important whitening ingredients, have been widely used in various skin care preparations. However, the application of kojic acid is limited by its poor stability and easy oxidation properties. In addition, allergic reactions and skin irritation problems occur commonly. Therefore, modifying the chemical structure of kojic acid to improve its stability, permeability, and biological activity has become a key research direction. Currently, the research on kojic acid derivatives mainly focuses on improving their skin stability and bioavailability through molecular modification (such as esterification and salification), thereby enhancing their activities such as whitening, antioxidation and anti-aging. These derivatives have shown good effects in whitening, protection against ultraviolet damage, and anti-inflammation, and have broad application prospects. With the progress of preparation technology, their application in skin care will be more extensive in the future. This review aims to systematically analyze the application progress of kojic acid and its derivatives in cosmetic preparations, explore their action mechanisms, research status, and the challenges faced, and provide theoretical support for subsequent research in related fields.