<p>Activated carbon derived from coconut shell waste has attracted considerable attention as a sustainable adsorbent for water treatment due to its high carbon content and tunable porous structure. However, the interplay between activation strategies, resulting physicochemical properties, and practical adsorption performance remains inconsistently interpreted across studies. This review critically synthesises current research to establish structure–property–performance relationships governing coconut-shell-derived activated carbon. Comparative analysis reveals that although chemical activation often enhances surface area and microporosity, higher surface area does not universally translate into superior adsorption capacity. Instead, pore size distribution, surface functional groups, and adsorbate–adsorbent compatibility play equally decisive roles in determining removal efficiency and adsorption kinetics. Quantitative benchmarking highlights significant variability in reported capacities due to inconsistent operating conditions, underscoring the need for standardised evaluation metrics. Regeneration studies indicate moderate capacity retention across cycles, yet structural degradation, pore blockage, and energy-intensive reactivation remain critical challenges for long-term application. Furthermore, the review evaluates sustainability trade-offs associated with chemical activation, including reagent consumption, secondary effluent generation, and environmental burden, and discusses greener alternatives and resource-efficient strategies. By integrating adsorption performance, cyclic stability, and sustainability considerations, this work provides a comprehensive framework for rational design and scalable implementation of coconut-shell-derived activated carbon. in water treatment systems.</p>