Strain sensors and bionic skin made of hydrogels have been rapidly developed for use in human motion detection. However, the realization of self-powered sensing using hydrogels has huge application prospects and challenges. Herein, a fruit-battery-inspired economical self-powered hydrogel-based sensor was designed and fabricated, and it integrates high stretchability (∼830%), a skin-like Young's modulus (∼30 kPa), good electrical conductivity (∼5.3 S m⁻¹), anti-drying and anti-freezing (−47.92 °C) properties, transparency (92.92%, thickness: 3 mm), and a suitable output voltage (∼0.55 V). More importantly, a new self-powered strain sensing mechanism based on this hydrogel was proposed. The self-powered hydrogels can respond to pressure and strain signals through output current changes without the use of an external power supply. Finally, self-powered ionic skin consisting of 8 hydrogel sensor units was assembled and it achieved a maximum output voltage of ∼4.4 V. The ionic skin can provide emergency power for types of small equipment (LED bulbs and buzzers). This study provides new concepts and ideas for self-powered sensors that are suitable for use in extreme environments.