<p>The performance of membrane processes is inherently linked to the properties of the membranes used, which can be significantly enhanced through post-treatment techniques. This review provides a thorough examination of various post-treatment methods employed to tailor the surface properties, improve selectivity, and enhance the stability of membranes in different separation processes. The paper begins by detailing specific post-treatment methods, including surface grafting, crosslinking, thermal treatment, reagent soaking, and the formation of additional modification layers such as surface coating, chemical vapor deposition, molecular layer deposition, polyphenol chemical vapor deposition, and in situ growth. Each section elucidates the underlying mechanisms and types of reactions involved in these processes, offering insights into how they can be controlled to achieve desired outcomes. Furthermore, the review explores the application of these post-treatment strategies in various membrane processes, such as reverse osmosis, nanofiltration in aqueous and organic solvent systems, forward osmosis, gas separation, pervaporation, and osmotic power generation. The significance of this work lies in its comprehensive analysis of how post-treatment can be leveraged to address specific challenges in membrane technology, thereby contributing to the advancement of more efficient and sustainable separation processes. The review concludes by emphasizing the need for a deeper understanding of the interplay between post-treatment techniques and membrane materials, as well as the development of novel strategies that combine multiple methods to achieve synergistic improvements in membrane performance.</p>