With the comprehensive promotion of ultralow emissions and world-class energy consumption standards, the disposal of the spent SCR (selective catalytic reduction of NOx with NH3) catalyst and fly ash has become a new challenge for coal power plants. In this study, a new method of simultaneous utilization of the spent SCR catalyst and fly ash in concrete preparation was developed. The working performance and heavy metal leaching characteristics of concrete prepared by replacing some cement with the spent SCR catalyst/fly ash were investigated. Results suggested that the addition of fly ash could improve the deterioration of concrete fluidity caused by the addition of the spent SCR catalyst. Better working performance was evidenced at 5% of the spent SCR catalyst and less than 10% of fly ash addition. When more than 10% of the spent SCR catalyst was added into concrete, the compressive strength and impermeability of the concrete were significantly worsened, but those could be improved by adding fly ash due to its pozzolanic activity. Leaching characteristics showed that the solidification efficiency of V and As could reach more than 96 and 97%, respectively, which mainly comes from the generation of C-S-H gels by the hydration reaction of cement in the concrete curing process. Results revealed that the method proposed in this study can achieve high-efficiency solidification of heavy metals in spent SCR catalysts. In general, the simultaneous utilization of the spent SCR catalyst and fly ash to replace some parts of the cement for preparing concrete is a promising method for harmless disposal of spent SCR catalysts.