Current research on heterogeneous advanced oxidation processes (HAOPs) predominantly emphasizes catalyst iteration and innovation. Significant efforts have been made to regulate the electron structure and optimize the electron distribution, thereby increasing the catalytic activity. However, this focus often overshadows an equally essential aspect of HAOPs: the adsorption effect. Adsorption is a critical initiator for triggering the interaction of oxidants and contaminants with heterogeneous catalysts. The efficacy of these interactions is influenced by a variety of physicochemical properties, including surface chemistry and pore sizes, which determine the affinities between contaminants and material surfaces. This disparity in affinity is pivotal because it underpins the selective removal of contaminants, especially in complex waste streams containing diverse contaminants and competing matrices. Consequently, understanding and mastering these interfacial interactions is fundamentally indispensable not only for improving process efficiency but also for enhancing the selectivity of contaminant removal. Herein, we highlight the importance of adsorption-driven interfacial interactions for fundamentally elucidating the catalytic mechanisms of HAOPs. Such interactions dictate the overall performance of the treatment processes by balancing the adsorption, reaction, and desorption rates on the catalyst surfaces. Elucidating the adsorption effect not only shifts the paradigm in understanding HAOPs but also improves their practicality in water treatment and wastewater decontamination. Overall, we propose that revisiting adsorption-driven interfacial interactions holds great promise for optimizing catalytic processes to develop effective HAOP strategies.