Flexible supercapacitors are potential to power next‐generation flexible electronics. However, the mechanical and electrochemical stability of flexible supercapacitors under different flexible conditions is limited by the weak bonding between adjacent layers, posing a significant hindrance to their practical applicability. Herein, based on the uninterrupted 3D network during the growth of bacterial cellulose (BC), w e have cultivated a flexible all‐in‐one supercapacitor through a continuous biosynthesis process. This strategy ensures the continuity of the 3D network of BC throughout the material, thereby forming a continuous electrode‐separator‐electrode structure. Benefitting from this bioinspired structure, the all‐in‐one supercapacitor not only achieves a high areal capacitance (3.79 F cm⁻²) of electrodes but also demonstrates the integration of high tensile strength (2.15 MPa), high shear strength (more than 54.6 kPa), and high bending resistance, indicating a novel pathway towards high‐performance flexible power sources.

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