Silver-zinc (Ag-Zn) fibrous batteries are considered as a promising power source for next-generation flexible/wearable electronics because of their superior safety, high energy density, and stable output voltage. Nevertheless, the widespread application of Ag-Zn batteries is hindered by their limited cycle life, primarily caused by Zn dendrite growth and Ag migration. Herein, we develop a flexible mild Ag-Zn fibrous battery with outstanding cycle performance via designing a bifunctional gel electrolyte. The graphene oxide (GO) introduced into the electrolyte provides dual enhancement in suppressing the growth of Zn dendrite and migration of Ag, leading to improved structural integrity and long cycle life. The designed fibrous battery demonstrates a high capacity of 0.85 mAh cm−1 and it can retain 90% (77.4%) of the initial capacity after 250 cycles under current density of 0.5 (5) mA cm−1. Additionally, the battery can maintain its performance under various deformations and a four-battery set is employed as the power source for LED patterns and wearable sensors. This work provides a rational way to design advanced gel electrolytes for high-performance flexible batteries.