Developing soft devices for invasive procedures bears great importance for human health. The softness and large strain actuation of responsive hydrogels promise the potential to fabricate soft devices, which can attach on and assist to the function of organs. The key challenges lie in the fabrication of soft devices with robust actuating ability and biocompatibility to the attached organ. This paper presents a solution that integrates the thermoresponsive hydrogel membrane with flexible electronics and silk scaffold into a balloon‐like soft device. As an example, the actuation assisting function of this soft device for shrinking an animal bladder is presented. The mechanical behaviors of the balloon‐like soft device are experimentally and theoretically investigated. The concepts are applicable to other applications such as soft implants, soft robotics, and microfluidics.