With the rising development of flexible and wearable electronics, corresponding flexible energy storage devices with high energy density are required to provide a sustainable energy supply. Theoretically, rechargeable flexible Li–O2 batteries can provide high specific energy density; however, there are only a few reports on the construction of flexible Li–O2 batteries. Conventional flexible Li–O2 batteries possess a loose battery structure, which prevents flexibility and stability. The low mechanical strength of the gas diffusion layer and anode also lead to a flexible Li–O2 battery with poor mechanical properties. All these attributes limit their practical applications. Herein, the authors develop an integrated flexible Li–O2 battery based on a high‐fatigue‐resistance anode and a novel flexible stretchable gas diffusion layer. Owing to the synergistic effect of the stable electrocatalytic activity and hierarchical 3D interconnected network structure of the free‐standing cathode, the obtained flexible Li–O2 batteries exhibit superior electrochemical performance, including a high specific capacity, an excellent rate capability, and exceptional cycle stability. Furthermore, benefitting from the above advantages, the as‐fabricated flexible batteries can realize excellent mechanical and electrochemical stability. Even after a thousand cycles of the bending process, the flexible Li–O2 battery can still possess a stable open‐circuit voltage, a high specific capacity, and a durable cycle performance. A novel integrated self‐package flexible Li–O2 battery is developed with a stable composite anode and flexible gas diffusion layer. Excellent mechanical stability and superior battery performances are successfully achieved under different shapes and even after repeated mechanical twisting, bending processes, showing high promise to power next generation versatile flexible electronics.