Abstract The adaptable, modular structure of muscles, combined with their confluent energy storage allows for numerous architectures found in nature: trunks, tongues, and tentacles to name some more complex ones. To provide an artificial analog to this biological soft muscle, a self‐powered, soft hydrostat actuator is presented. As an example of how to use these modules, a worm robot is assembled where the near totality of the body stores electrochemical potential. The robot exhibits an extremely high system energy density (51.3 J g −1 ), using a redox flow battery motif, with a long theoretical operational range of more than 100 m on a single charge. The innovation lies in the battery pouch, fabricated with a dry‐adhesion method, automatically bonding Nafion separators to a silicone‐urethane copolymer body. These pouches contain anolyte within a hydrostat pod filled with catholyte, increasing current density per pod. Each pod has a motor and tendon actuator for radial compression and expansion. By linking these self‐contained pods in series, the robot worm is created that automatically navigates an enclosed, curved path. This high‐capacity soft worm also climbs up and down a vertical pipe, using a two‐anchor crawling gait, with an extra payload equivalent to 1.5 times its body weight.