Bio-electro-Fenton processes use biological electrons produced from bioelectrochemical systems to treat wastewater. The most significant advantages of bio-electro-Fenton systems are high effectiveness, low toxicity, gentle operation conditions, environmentally friendly treatment without sludge accumulation and energy conservation. Though promising, bio-electro-Fenton systems still face several challenges, such as high power density, H2O2 concentration, cathode materials, Fe2+ concentration and pH. This review comprehensively discusses the mechanisms of bio-electro-Fenton systems. Then, structural configurations are critically reviewed, including microbial fuel cells coupled with electro-Fenton systems, microbial electrolysis cells coupled with electro-Fenton systems and other bioelectrochemical systems coupled with electro-Fenton systems. Furthermore, recent advances in bio-electro-Fenton systems for wastewater treatment are introduced, including dye solution, pharmaceuticals and personal care products, oily wastewater, landfill leachate and other pollutants. In addition, the current challenges and specific future prospects of bio-electro-Fenton, such as possible mechanisms for improving the power output, electrode materials that are potentially useful, self-designed electrodes and methods of maintaining circumneutral pH values, are also explored. Heretofore, great progress in bio-electro-Fenton has been made, but further improvements are still needed in order to make this system more economical and practical. (c) 2020 Society of Chemical Industry