In the present work, zinc tungstate (ZnWO₄) nanoparticles were synthesized by a simple co-precipitation technique without the addition of any templates and complexing agent. The X-ray diffraction study confirmed the formation of monoclinic structure ZnWO₄. The annealing temperatures play a significant role on the crystallization of the samples and the crystallite size of ZnWO₄ nanoparticles are varied between 30 and 65 nm. The well dispersed spherical solid shells along with nanoplatelet like morphology was obtained from the surface morphological study. The concomitant decrease in optical energy band gap value of ZnWO₄ is due to the effect of crystallite size enhancement. It was observed that the crystallinity is one of the primary factors that affect the luminescence property of ZnWO₄ nanoparticles. The purity and stoichiometric nature of synthesized product was confirmed by compositional analysis. The highest degradation efficiency of 87% was observed for 300 °C annealed ZnWO₄ nanoparticles in the photocatalytic study by the degradation of methylene blue dye under ultraviolet light irradiation. The photocatalytic study confirmed the decomposition of methylene blue after 1 h irradiation.