Polymeric coatings with micro-spherical morphology have a high surface area, which is advantageous for resins for heterogeneous chemical catalysis, for adsorption processes, nano-reactors, and anti-fouling coatings for water treatment membranes. The fabrication of stable, non-leachable micro-spherical polymers on solid surfaces is challenging. Here we introduce a straightforward method for fabricating polymeric particles with micro-spherical morphology on poly(ethylene terephthalate) fibers used as media for water filtration in microfiber technology. UV-initiated grafting with poly(ethylene glycol) methacrylate (PEGMA) monomers using benzophenone in aqueous solutions resulted in stable spherical particles coated on poly(ethylene terephthalate) threads, as revealed by FTTR, gravimetric degree of grafting, and SEM analyses. The micro-spherical morphology was unique to grafting with PEGMA monomers, whereas other types of methacrylate monomers resulted in smooth coatings. Grafting with PEGMA on high-flux water filtration cassette made of poly(ethylene terephthalate) fibers lead to enhanced performance and better dust removal capacity of the filter. The improved performance in coarse filtration is beneficial for treatment of water for agriculture, pretreatment facilities for freshwater supply, cooling water systems, and wastewater treatment. The protocol developed in this study is highly promising for both industrial and medical applications.