Ruthenocenyl glycidyl ether (rcGE) is a novel monomer for the anionic polymerization and copolymerization with ethylene oxide to water-soluble, thermo-, and redox-responsive organometallic poly(ethylene glycol)s (PEGs). The polymers exhibit adjustable molecular weights, comonomer ratios, and narrow molecular weight distributions (typically Mw/Mn < 1.2). Real-time 1H NMR copolymerization kinetics prove random incorporation of rcGE into the polyether backbone in analogy to its ferrocene analog. The rcGE-co-EO copolymers are water-soluble with a lower critical solution temperature, depending on the rcGE content. Terpolymerization of ferrocenyl glycidyl ether, ethylene oxide, and rcGE produces the first random PEG derivatives with multiple redox response. Ruthenocenyl glycidyl ether broadens the field of organometallics, especially ruthenium-containing polymers, and these copolymers might find applications in catalysis, as redox-active surfactants, or as staining reagents in electron microscopy.