This work reports a facile and large-scale synthesis of ZnO nanoparticles by simple self-propagating solution combustion method using dextrose as fuel and their effective use as a photocatalyst for photocatalytic degradation of Direct Red-23 (DR-23) dye in an immersion well type photo-reactor. The prepared ZnO nanoparticles were characterized by various analytical tools using field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) pattern, Fourier transform infrared (FTIR) spectroscopy and UV-Vis. spectroscopy measurements. The detailed characterizations confirmed that the prepared ZnO nanoparticles are pure, well-crystalline and possessing wurtzite hexagonal phase. Almost complete photo-degradation of the DR-23 was observed in 110 min. under UV irradiation in presence of ZnO nanoparticle photocatalyst. This study reveals that simply prepared ZnO nanomaterials are effective photocatalyst for the photocatalytic degradation of various toxic chemicals and pollutants.