Nitrogen-doped three-dimensional (3D) graphene foam (GF) has aroused tremendous interest for the supercapacitors (SCs) applications because of its unique properties. However, it is still confronting the challenges of facile preparation and the high N-doping level. Here, by rolling a part of graphene planes into the fiber-like scaffold to support other graphene sheets, we obtain high-quality 3D GF. Followed by fluorination and N-doping, N-superdoped GF (NGF) with N content as high as 15.7 at.% was successfully prepared. The combination of fiber-supported 3D structure and high N-level facilitate forming GF with large surface area, low internal resistance, good wettability, and sufficient active sites, which results in high-performance SCs: The prepared NGF electrode has a high specific capacitance (320.0 F g(-1) and 303.5 F g(-1) in three- and two-electrode system, respectively), and a long cycle life (92.8% retention after 1000 cycles), as well, the NGF SC device has a high energy density (42.1 Wh kg(-1) at 250 W kg(-1)).