The paper presents the results of numerical modeling of the compaction and grain growth processes of powder materials based on zirconium dioxide ZrO2 during electroconsolidation. The theoretical basis is the Skorokhod–Olevskyi–Shtern model, which describes the kinetics of compaction and the evolution of microstructure. The model parameters were identified based on experimental data on the changes in temperature, relative density, and axial stress of samples with a composition ZrO2 + 3 mol % Y2O3. A specialized computer program was developed, which allowed a series of numerical experiments to be performed and the simulation results to be compared with actual sintering data. It was found that the calculated density change curves closely match the experimental results, confirming the adequacy of the model used. It has been shown that grain growth significantly affects the final stages of the process, but the final density is largely determined by the isothermal holding mode and the level of pressure applied. It has been demonstrated that increasing the pressure allows to achieve high density even without significantly prolonging the process time. The developed approach provides the ability to predict the density, grain size, and mechanical properties of sintered samples. The practical significance of the work lies in the fact that the proposed method can be used to optimize electroconsolidation modes, reduce energy consumption, and improve the quality of ceramic zirconium composites.