The work aims to obtain graphene/nanocellulose/manganese dioxide (GE/CNFs/MnO2) composite aqueous fiber supercapacitor with excellent electrochemical performance. The GO/CNFs/MnO2 mixed spinning solution was pre-pared by ultrasonic dispersion treatment. The wet-spinning strategy was adopted to obtain GO/CNFs/MnO2 composite fiber electrode. Then, the GE/CNFs/MnO2 composite fiber electrodes with the porous structure were constructed by hydroiodic acid and freeze-drying treatment. Finally, the two-electrode aqueous supercapacitor was formed through assembly. In the GE/CNFs/MnO2 composite fibers, the addition of CNFs effectively inhibited the self-aggregation of graphene sheets and significantly improved the hydrophilicity and tensile strength of composite fiber. The addition of MnO2 significantly improved the electrochemical performance of the fiber electrode. Due to careful experimental design, GE/CNFs/MnO2 composite fiber had a tensile strength of 338 MPa. The assembled aqueous supercapacitor had superior capacitance performance and cyclic stability. When the current density was 0.1 mA/cm2, the area capacitance was 412.5 mF/cm2, and the capacitance retention rate was 87% after 1500 cycles. GE/CNFs/MnO2 aqueous supercapacitor prepared through practical wet spinning strategy combined with a carefully designed electrode structure provides an excellent reference for the development of wearable portable energy storage devices and intelligent packaging energy supply systems.