The demand for wearable electronics is still growing, and the rapid development of new electrochemical materials and manufacturing processes allows for innovative approaches to power these devices. Here, three-dimensional (3D) self-supported reduced graphene oxide/poly(3,4-ethylenedioxythiophene) (rGO/PEDOT) hybrid fiber fabrics are systematically designed and constructed via phase inversion-based microfluidic-fiber-spinning assembly (MFSA) method, followed by concentrated sulfuric acid treatment and chemical reduction. The rGO/PEDOT fiber fabrics demonstrate favorable flexibility, interconnected hierarchical network, large specific surface area, high charge storage capacity, and high electrical conductivity. In addition, the all-solid-state supercapacitor made of these rGO/PEDOT fiber fabrics proves large specific capacitance (1028.2 mF cm-2), ultrahigh energy density (22.7 μWh cm-2), long-term cycling stability, and excellent flexibility (capacitance retention remains at 84%, after 5000 cycles of continuous deformation at 180o bending angles). Further considering those remarkable electrochemical properties, a wearable self-powered device with a sandwich-shaped supercapacitor (SC) is designed to impressively light up LEDs and power mini game console, suggesting its practical applications in flexible and portable smart electronics.