Conductive hydrogels are of significant interest for a broad range of applications, including electronic skin, cardiovascular tissue engineering, implantable or wearable biosensors for human health monitoring. This work presented interesting results on a graphene oxide hydrogel based on mussel chemistry. The hydrogel simultaneously possesses the following remarkable properties. The hydrogel had good conductivity (0.1 S/cm) and maintained a stable conductivity during repeatable extension and compression cycles. The hydrogel performs superior mechanical properties with large stretch strain of 3800%, and high toughness of 6870 J/m2, due to the synergistic reinforcing effects of graphene oxide (GO) and polydopamine (PDA) in the hydrogel. The hydrogel could directly self-adhere on human body without additional adhesives. In addition, the hydrogel could self-heal under the ambient environment without other external stimuli, which facilitated it self-healing after unfavorable damage and expand its lifetime in usage. The hydrogel has good biocompatibility, which enhances the flexibility to apply inside human body. By combining those properties, the novel conductive hydrogel has the potential to serve as bioelectronics not only regulating cell activity but also detecting or applying signals in invasive systems contacting with living tissues. Thus, the conductive and self-adhesive hydrogel leads to a new class of implantable and flexible bioelectronics for human body, which is softer and easier to be used. The facile method opens new avenues for the conductive hydrogels with multi-functions to have more practical applications in diverse areas.