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Three-dimensional (3D) ceramic network has advantages over conventional ceramic nanoparticles in achieving high-performance flexible polymer dielectrics. However, the energy storage capacity cannot be substantially improved due to the relatively large dielectric loss and low breakdown strength. In this study, hierarchical 3DBT/EP-GO (GEBT) dielectric hybrid composites with greatly improved permittivity and energy storage density were obtained by reversely introducing the mixed graphene oxide (GO)/epoxy (EP) solution into three-dimensional BaTiO3 (3DBT) network, which was facilely constructed by sol-gel method using cleanroom wiper as template. A relatively high dielectric constant (ε′ = 15.6) and breakdown strength (E0 = 239.8 kV·mm− 1) were simultaneously achieved for the GEBT-4 system with ~ 15.4 wt% of 3DBT and 0.75 wt% of GO (to the epoxy), which were much superior to the GEBT-1 with only 15 wt% 3DBT (ε′ = 9.2, E0 = 128.8 kV·mm− 1) and epoxy nanocomposite with even 25 wt% BT nanoparticles (ε′ = 6.3, E0 = 121.0 kV·mm− 1). The continuous 3DBT ceramic network provided effective polarization pathway within epoxy matrix, while GO was helpful to prevent electrical breakdown of composites, thereby resulting in the significantly enhanced energy storage performance.