ZnS nanoparticles with 90 nm diameter were synthesized by low-temperature method and immobilized onto the surface of polyvinylidene fluoride (PVDF) pellets prepared by phase inversion method. Results by FTIR and X-ray photoelectron spectroscopy revealed that the ZnS nanoparticles were immobilized tightly on the PVDF surface without their release and losing photocatalytic activity. The UV-absorption spectra showed that the PVDF matrix had no adverse effect on the optical properties of ZnS nanoparticles. Due to large size (5 mm) and excellent mechanical stability, the PVDF-ZnS pellets could be easily dispersed in the photocatalytic reactor treating methylene blue solution. The removal efficiency of the methylene blue with the PVDF-ZnS pellets was higher (more than 95%) than that observed by the control PVDF pellets or ZnS nanoparticles tested. No change in the removal efficiency was observed as the PVDF-ZnS pellets were reused by performing photocatalytic tests at the same experimental conditions repeatedly.