Mechanochemical engineering offers a green, solvent-free or solvent-minimized approach to producing advanced nanomaterials in the fields of water and wastewater treatment. Through the utilization of mechanical forces via ball milling, solid-state grinding, and twin-screw extrusion, many chemical transformations can be performed in light or ambient conditions without the need for toxic solvents, high temperatures, or complicated reactions. This review examines recent developments in mechanochemical synthesis of adsorbent materials with an eye toward their structure, surface design, and performance in the removal of dyes, heavy metals, pharmaceuticals, and emerging persistent contaminants. Mechanochemical activation produces defects, enhanced porosity, heteroatom incorporation, and accessibility of reactive surface sites, which improves adsorption and multi-functional contaminant removal. Aside from the material aspects, this review discusses process aspects such as scalability, integration into actual treatment systems (e.g. membranes and packed bed reactors), regeneration efficiency, and overall environmental sustainability. This review concludes that mechanochemically synthesized adsorbents can perform comparably to or better than conventionally prepared materials while requiring less solvent, energy, and waste generation. But mechanochemistry provides a powerful and sustainable route to develop new adsorbent materials in line with green and sustainable water treatment practices. Continuous reactive extrusion, in situ characterization, and artificial intelligence (AI) may enable consistent, scalable production of next-generation adsorbents. Graphical abstract