Although the hydrogel electrolytes for flexible energy-storage device have made great progress, it still remains a huge challenge to assemble a smart supercapacitor with high ionic conductivity and excellent self-healing when suffering physical damage. Herein, a novel self-healing hydrogel electrolyte (B-PVA/KCl/GO) is designed and prepared through graphite oxide (GO) doped into a diol-borate ester bonding cross-linked poly(vinyl alcohol) network. It is found that the moderate amount of GO-doped into hydrogel (2.3 wt% GO, 47.5 mS/cm) is obviously improved ionic conductivity compared with bare B-PVA/KCl hydrogel (32.6 mS/cm). Interestingly, the B-PVA/KCl/GO hydrogel electrolyte exhibits excellent self-healing capability that can repair its original configuration with 5 min when it is cut. Moreover, the activated carbon-based supercapacitor with B-PVA/KCl/GO hydrogel electrolyte delivers high specific capacitance of 156 F g−1 at 0.3 A g−1 and can also restore its capacitive performances via 7 times healing cycles without external stimulus. The presented work provides a new strategy to construct a flexible and self-healing hydrogel to apply for wearable electronics, smart apparels or flexible robots.