Flexible energy storage devices are at the forefront of next-generation power supplies, one of the most important components of which is the gel electrolyte. However, shortcomings exist, more or less, for all the currently developed hydrogel electrolytes. Herein, a facile and cost-effective method is developed to construct an all-round hydrogel electrolyte by using cotton as the raw material, tetraethyl orthosilicate as the crosslinker, and glycerol as the antifreezing agent. The obtained hydrogel electrolyte has high ionic conductivity, excellent mechanical properties (e.g., high tensile strength and elasticity), ultralow freezing point, good self-healing ability, high adhesion, and good heat-resistance ability. Remarkably, this hydrogel electrolyte can provide a record-breaking high ionic conductivity of 19.4 mS cm