Chloro- and bromo-avobenzone are chlorinated and brominated derivatives of avobenzone(4- tertbutyl-4-methoxy dibenzoylmethane). A widely used UVA filter in sunscreens, avobenzone is a widely used UVA filter in sunscreens. When avobenzone is released from sunscreen through wash-off into swimming pools or natural waters, it reacts with chlorine and bromine, forming chloro- and bromo-avobenzone. These halogenated compounds are considered Emerging Disinfection By-products(DBPs). These derivatives are more toxic and environmentally persistent than the parent compound, highlighting the need for their effective removal to protect aquatic ecosystems. Toward this goal, the present study explored a sunlight/H2O2 system as a viable approach for the decontamination of water contaminated with chloro- and bromo-avobenzone. Water treatment using H2O2 under sunlight to conversion of chloro and bromo-avobenzone back to parent avobenzone, it provides an effective advanced oxidation strategy for contaminant degradation. Photodegradation profiles have been evaluated under sunlight using hydrogen peroxide(H2O2). Chloro- and bromo-avobenzone were synthetically prepared, their molecular properties computed, and their H2O2 induced degradation under UV light and sunlight was evaluated. The resulting photodegradation products were characterized using UV–Vis spectroscopy and LC–ESI-MS, and putative structures of the by-products were deduced. Sunlight-induced degradation of chloro- and bromo-avobenzone in the presence of H2O2 over an entire day primarily yielded oxidative products of avobenzone and its smaller fragments. The intensity of sunlight varied between 15–35 W/m², displaying a Gaussian distribution with a peak around 12:30 PM. This newly developed oxidation method represents an eco-friendly and low-cost approach for the decontamination of chloro- and bromo-avobenzone and may serve as a valuable tool for the treatment of diverse water bodies, including those in rural areas.