AbstractReverse electrodialysis (RED) is an eco‐friendly power generation system that produces electricity from the salinity difference between two solutions of different concentrations. Recently, research on RED has expanded not only to increase the maximum power density, but also to converge with other energy generation systems. Most importantly, miniaturized RED has been developed rooted on its nature, such as convenient customization and electrodeless character. This RED, being compact and readily disposed, functions as a unique type of power source, operating solely by the flow of ions, which is thus perfectly compatible to integrate with various bio‐related systems. We emphasize the potential of this RED as a hybrid, disposable, portable and fully ionic power source and look forward to its wide range of application scopes in the future.