3D-Printed supercapacitive graphene electrodes often face significant challenges, such as high interfacial impedance and restricted ion diffusion at the microscopic level, leading to poor capacitance scaling, reduced energy delivery, and constrained kinetic performance. To address these issues, poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) is employed as an interface mediator. Phase-engineering of PEDOT:PSS enables the formation of conformation-driven percolative interfaces, establishing bicontinuous reaction fronts that improve electron transport and ion diffusivity. Consequently, 3D-printed highly loaded supercapacitors successfully accommodate ultra-high energy density and excellent kinetic performance. This approach effectively mitigates the inherent limitations of 3D-printed graphene electrodes, facilitating their use in energy-intensive electronic devices.