Polyoxometalate (POM)-based metal-organic frameworks (MOFs) are extended structures containing polyoxometalate units with open networks that offer the advantages of both POMs and MOFs materials. Polyoxometalate-based metal-organic frameworks have attracted much attention in the fields of material science not only because of their diverse structures and topologies, but also because of their potential applications in catalysis, adsorption and separation, proton conduction, magnetism, electrochemistry, medicine, and other fields. In particular, polyoxometalates with strong acidity, multi-electron redox properties, and photoactivity combined with the high surface area and tunable pore size of MOFs make them excellent heterogeneous catalysts in various catalytic reactions.