3D ultra-thin carbon networks are ideal skeleton structures for loading active materials as energy storage and conversion devices. In this work, excellent cathode materials for sodium ion batteries were successfully prepared by homogeneously anchoring NaxKyMnFe(CN)6 (x + y ≤ 2, NaK-MnHCF) on hierarchical porous 3D N-doped ultra-thin carbon networks (3DNC). The compounds present a high reversible capacity, good rate performance, and superior cycling stability. Combined fully experimental analysis and first-principles calculation, the interfacial synergistic effect between 3DNC and NaK-MnHCF on the sodium storage capacity is revealed, contributing to the extra capacity and electrical conductivity. Furthermore, considerable content of capacitive-controlled sodium storage of NaK-MnHCF@3DNC conduces to the rate performance. These results reveal an efficient route for the fabrication of other cathode materials for sodium ion batteries as high-performance energy storage devices.