We report a supramolecular strategy to fabricate high-doping-leveled (10.5 at.%) porous nitrogen-doped reduced graphene oxide (P-NrGO) with outstanding electrochemical properties as electrode material for supercapacitors. The introduced supramolecular polymers melamine cyanurate (MC) acts a barrier to prevent the graphene sheets from restacking, and meanwhile functions as a soft template to create porous structure as well as nitrogen source for in-situ N-doping. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images show that the P-NrGO exhibits wrinkled and loose-packed thin layer structure with a large number of pores. X-ray photoelectron spectrometer (XPS) spectra demonstrate that pyridine and pyrrole-N was the main nitrogen bonding states, which were favorable for the improvements of supercapacitive performance. Attributed to the synergistic effects of the porous structure and the N-doping, the P-NrGO1 exhibits an increase of 56.5% in the specific capacitance (335 F g−1) when compared with the rGO (214 F g−1). In addition, the capacitance retention ratio reaches 94.3% after 10000 cycles, indicating the excellent electrochemical stability. The present work benefits the large-scale production of N-doped graphene oxide for high-performance supercapacitors.