Photocatalysis under solar irradiation is an economically viable technique for the treatment of environmental contaminants. A ternary nanocomposite (TNC) has been synthesized by a hydrothermal technique and characterized by various techniques. XRD confirmed the crystallinity and supported the formation of ZnO and CeO2 phases in TNC. FE-SEM showed that the nanocomposite containing ZnO and CeO2 were nanosized and arranged in the rGO nanosheets. The particle size was found to be 20–30 nm. The photocatalytic studies were conducted for the degradation of orange G dye (Azo dye) under solar light irradiation. Out of the five ratios of nanocomposites prepared TNC1, TNC2, TNC3, TNC4 and TNC5, TNC4 showed better photocatalytic activity. Systematically, the preliminary and kinetic studies were conducted. The effect of variation of aqueous phase pH, catalyst dosage and concentration of dye showed 10 mg/10 ml of 10 ppm Orange G dye in neutral pH to degrade (> 99%) in 1 h of irradiation. A decrease in absorbance and COD of the photocatalytically degraded Orange G confirmed the enhanced activity of the prepared TNC. The reaction was found to follow a pseudo-first-order kinetics. This study paves way for utilizing solar active photocatalyst for wastewater treatment. Graphical abstract: [Figure not available: see fulltext.]. © 2022 Elsevier B.V., All rights reserved.