Electrochemical energy storage plays a significant role in solving the issues of energy shortage and environmental pollution. Recently, polyoxometalates (POMs) have received significant attention as promising materials for electrodes in electrochemical energy conversion and storage devices. To improve electrochemical performance, POMs can be modified by a variety of techniques and methods. Their open frameworks, consisting of independent structural units that possess potential catalytic properties, can meet the requirements of cutting-edge technologies and demonstrate advantages over routine insertion-type open frameworks with limited one-electron transfer properties or conversion materials with compact ligand linkage. Here, a class of electrochemically stable cluster-like POMs are discussed for applications as open framework electrodes. In this paper, the latest research progress on POMs-based materials is introduced, and current applications in advanced electrochemical energy conversion and storage are highlighted; these applications include Li- and Na-ion batteries, redox flow batteries, and fuel cells.