Polyoxometalates (POMs) are inorganic polyacid clusters that can release multiple protons. Because of its high electrolyte solubility, poly(ethylene oxide) (PEO) is the most important matrix for solid electrolytes composed of polymer/electrolyte mixtures. We herein combined the characteristics of POMs and PEOs to develop proton-conducting solid electrolytes wherein both components are covalently linked to the main chain. After synthesizing the POM- and PEO-containing norbornene monomers, we prepared block and random hybrid copolymers (weight-average molecular mass of 270-470 kDa) composed of POM-polyelectrolyte complexes and PEO bottlebrush polymers via living ring-opening metathesis polymerization. When all organic cationic counterions associated with the POM pendant had been exchanged with protons, the molecular weights of the copolymer polyelectrolytes were similar to the theoretical values, implying that the copolymer remained intact. The proton conductivities were 111 and 30-35.7 mS cm(-1) for the random and block copolymer polyelectrolytes, respectively, at 80 degrees C and 100% relative humidity.