The rapid development of reversible deactivation radical polymerization (RDRP) enables the preparation of well-defined polymers with diverse topological architectures and functionalities. In particular, photoinitiated RDRP (photo-RDRP) has gained increasing attention in the past decade due to the use of environmentally friendly and economically benign external regulator, light. With the aid of photocatalysts, a great number of monomers could be polymerized to produce desired products under light irradiation. However, the uses of expensive transition metal complexes as photocatalysts lead to the significant rise in manufacture costs. Although many less expensive catalysts have been discovered, their toxicity and intense colour are still challenging. Therefore, catalyst separation processes are inevitable to obtain pure products. However, such purification processes are complicated and thus hinder the industrial applications. To this end, supported catalysts have been explored in photo-RDRP to facilitate the separation and reuse of the catalysts, hence accomplishing green and sustainable polymer synthesis. The body of work illustrates the benefits of supported catalysts in photo-RDRP as well as the robustness and versatility of these heterogeneous catalytic systems. Various innovative catalyst immobilization strategies have been proposed to prepare supported catalysts using cellulosic materials as solid supports. Afterwards, these supported catalysts were employed for photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization, in which various monomers were polymerized in different solvents under light irradiation to yield well-defined polymers with high end group fidelity. Moreover, facile separation and recovery of these supported catalysts were realized by simple squeezing and washing these catalyst immobilized composites, thus enable catalyst reuse with almost retained catalytic activity. More importantly, cotton supported free-base porphyrin has been further implemented into continuous flow reaction systems to afford well-defined polymers. In addition, cotton thread supported eosin Y was employed in organic transformations to yield desired organic compounds, thus provides a promising strategy for advanced macromolecular engineering in which polymer synthesis and subsequent functionalization could be conducted in one-flow reaction system without intermediate purification procedures.