Water system pollution by persistent organic compounds and emerging contaminants represents one of the major global environmental challenges. Due to their high chemical stability and bioaccumulative potential, these substances can remain in the environment for extended periods. Since they do not easily degrade, they accumulate and generate adverse effects even at exceedingly small concentrations on human health, plant and animal species, as well as on natural ecosystems. These negative effects include neurological, reproductive, hormonal, immunological, and cardiovascular alterations, in addition to being associated with diverse types of cancer. The limited effectiveness of conventional wastewater treatments against these substances has driven the development of advanced technologies aimed at mitigating these impacts. In this context, so-called advanced oxidation processes, and particularly heterogeneous photocatalysis, have emerged as one of the most efficient strategies for the mineralization and degradation of recalcitrant contaminants. The mechanism of heterogeneous photocatalysis is based on the excitation of a semiconductor catalyst through light absorption to generate electron-hole pairs (e−– h+), which react with water and oxygen to produce free radicals such as superoxide (O₂•−) and hydroxyl (OH•). These radicals have the capacity to attack and break down the complex molecular structures of contaminants, thereby decomposing them into less harmful compounds. This work provides an updated and well-founded perspective on the potential and limitations of ZnO in the design of advanced and sustainable solutions aimed at the degradation of recalcitrant contaminants for wastewater treatment.