Electrochemical oxidation processes (EOPs) have gained attention as promising technologies for the removal of refractory organic pollutants in water and wastewater. Although many reviews have been reported on EOPs, to date, no review has been mainly focused on the energy efficiencies of EOPs. Accordingly, herein, EOPs for the treatment of organic pollutants in water and wastewater are reviewed, and the performances of different EOPs in terms of energy efficiencies are evaluated using various figures of merit. The basic principles of EOPs are briefly introduced, and indicators for the performance evaluation of EOPs are analyzed based on the fundamentals and statistical databases of EOPs obtained from the literature. Electrical energy per order (EE/O) and electrical energy per mass (EE/M) have been widely used to measure the energy efficiencies of EOPs. However, statistical analysis indicates that EE/O is a more suitable index in this regard than EE/M because it better represents the kinetics of pollutant degradation by EOPs, thereby mitigating the influence of the initial organic load on the performance evaluation of EOPs. EOPs modified using Fenton’s reagent or external supplies of energy (or chemicals) exhibit higher energy efficiencies than those of anodic oxidation processes due to the existence of additional reactions or synergistic mechanisms for the generation of reactive oxidants. In addition to the evaluation of the energy efficiencies of different types of EOPs, the effects of electrode materials and electrolysis conditions, such as current density, pH, anions, and additive concentrations, on the energy efficiencies of EOPs are discussed. We believe that our review will provide useful information and insights for choosing the optimal types and conditions of EOPs for pollutant removal.