<p>This review focuses on the sustainable utilization of recycled polyethylene terephthalate (PET) in advanced filtration, distillation, and separation membranes. It addresses the critical problem of plastic waste management and the urgent need for sustainable materials in industrial applications. The main parts explored the structural modification of PET membranes, which analyzed various techniques and methodologies employed to modify the physical and chemical properties of PET membranes. The review highlights the importance of structural modifications in tailoring the membrane’s characteristics to fit specific application requirements. Additionally, it discusses emerging applications of PET membranes and presents novel and innovative uses in water treatment, gas separation, and membrane distillation. A significant part of the discussion evaluates the environmental implications and emphasizes the considerable reduction in waste and the conservation of resources through the recycling of PET. The challenges and prospects in the field of PET membrane technology were also discussed, which identified current limitations, proposed potential solutions, and set the direction for future research. This study is significant as it addresses the dual challenge of plastic waste reduction and the need for high-performance membrane materials in various industrial processes.</p>