Graphitic carbon nitride (g‐C₃N₄) has attracted much attention due to its unique polymeric structure of carbon and nitrogen in the form of heptazine units. In this study, a nickel catalyst supported on graphitic carbon nitride was prepared by a facile impregnation method. Ni/g‐C₃N₄ desorption and reduction behaviors with carbon monoxide (CO) were investigated by temperature‐programmed desorption (TPD) and reduction (TPR). The chemisorption study of reduction and desorption behaviors of CO molecules on Ni/g‐C₃N₄ catalyst is essential for CO methanation reaction. The as‐prepared Ni/g‐C₃N₄ catalyst was also characterized by X‐ray diffraction (XRD), N₂ physisorption, and X‐ray photoelectron spectroscopy (XPS). It was found that the utilization of g‐C₃N₄ as a catalyst support enhances the complete reduction of Ni species and CO desorption. This can be attributed to the role of g‐C₃N₄ support as a reducing agent for Ni, as well as its basicity owing to the richness of nitrogen functional group. The good performance of Ni/g‐C₃N₄ catalyst towards CO methanation can be ascribed to the improvement in adsorption and activation of CO molecules on the active sites and the number of surface basic sites.