Disinfection byproduct (DBP) formation during water and wastewater treatment is a concern for public health and environmental preservation. Dissolved organic nitrogen (DON) serves as a rec-ognized precursor to DBP formation, which can potentially jeopardize human health. This review article offers a comprehensive insight into DON's influence on DBP formation during water and wastewater treatment processes. It delves into DON's sources, properties, and concentrations in water and wastewater, underlining the variability dependent on water source and environmental conditions. The mechanisms of DBP formation from DON, encompassing formation pathways and influencing factors, are meticulously examined. Different treatment methods, like chlorina-tion, ozonation, and UV disinfection, are carefully examined to see how they affect the formation of DON and DBP. Factors that sway DON's impact on DBP formation are also explored. The review also presents various DBP reduction techniques, spanning physical, chemical, and biolog-ical treatment methods, their efficacy in curtailing DON's influence, and their potential pros and cons. It addresses challenges, outlines future research directions, identifies knowledge gaps, and highlights the necessity for regulatory measures and policies, providing recommendations for prospective research avenues. It is clear from this in-depth review that more research is needed to understand how DON affects the formation of DBP entirely. It is also essential to protect human health and the environment and follow the rules first when treating wastewater. In conclusion, it analyzes DON's part in forming DBP in water and wastewater treatment. This emphasizes the need for ongoing research and mitigation strategies to protect public health and water quality.