<p>This review investigates the photolysis of neonicotinoids—nicotine-derived insecticides—focusing on their environmental fates and degradation mechanisms. Since their introduction in the mid-1980s, neonicotinoids have grown in usage due to their systemic mode of action, which protects plants by circulating through their tissues. However, their extensive application has led to widespread dispersion into various environmental media, including soil, water, and air, with only a small fraction being absorbed by crops. The review emphasizes photolysis, driven by solar irradiation, as a primary degradation pathway for neonicotinoids in aquatic environments. This process is significantly influenced by water chemistry parameters such as pH, dissolved organic matter, inorganic ions, and temperature. The presence of anions and cations can regulate the formation of reactive species during photolysis, which in turn impacts degradation rates and the ultimate fate of neonicotinoids in aquatic systems. The review further outlines photodegradation pathways and the resulting photoproducts, emphasizing the need for additional research to assess their persistence and bioaccumulation potential in aquatic ecosystems. Future studies should integrate laboratory experiments and field approaches to elucidate how multiple environmental factors collectively affect photolysis rates and degradation byproducts. Additionally, developing advanced oxidation processes tailored to boost neonicotinoid photodegradation in contaminated environments represents a promising direction for future work. This knowledge will be instrumental in guiding strategies to mitigate neonicotinoids contamination, thereby safeguarding aquatic ecosystems and promoting sustainable agricultural practices.</p>