Biomimetic cross-linked polymersomes that exhibit a self-beating motion without any on-off switching are developed. The polymersomes are made from a well-defined synthetic thermoresponsive diblock copolymer, and the thermoresponsive segment includes ruthenium catalysts for the oscillatory chemical reaction and vinylidene groups to cross-link the polymersomes. Autonomous volume and shape oscillations of the cross-linked polymersomes are realized following redox changes of the catalysts.