As global warming worsens, countries around the world have developed policies to reduce carbon emissions and accelerate the transition to renewable energy systems. Recently proposed cement-based supercapacitors have attracted much attention due to their low energy consumption and multifunctionality, offering a promising solution for large-scale energy storage in renewable energy systems. This paper comprehensively summarizes the development, energy storage mechanism, and characterization techniques of cement-based supercapacitors, as well as the mechanical and electrochemical properties of the cement-based electrolytes. The paradoxical relationship between the energy storage capacity and mechanical properties of cement-based supercapacitors has been revealed. In addition, three energy storage modes including electrical double-layer (EDL) at the electrolyte–electrode interface, redox reaction in supercapacitors, and electrolyte charge storage have been reviewed. There is an optimum water/cement ratio for cement-based electrolyte. The type of cement and the content of additives have varying effects on the compressive strength, electrical conductivity, and energy storage capacity. The electrodes, which are the main source of pseudo-capacitance, considerably influence the electrochemical properties. The one with high surface area and chemical stability can offer a high capacitance and cycling stability for the supercapacitor. Furthermore, the performance of cement-based supercapacitors can be further enhanced by proper selection of electrode and electrolyte. It is expected that this review will not only provide direction for those engaged in energy storage, but also important ideas for achieving the goal of energy saving and carbon neutrality.