This research was aimed at fabrication and characterization of novel hybrid carbon-fiber/epoxy composites reinforced with toughening/self-repairing nanofibers at interfaces. For interfacial toughening, continuous electrospun polyacronitrile (PAN) and carbon nanofibers (CNFs) were incorporated between carbon fabrics to form the ultrathin toughening interlayers after resin infusion and curing. Mode I interlaminar fracture tests showed that PAN nanofibers can noticeably enhance the fracture toughness of Epon 862 based composites, while the toughening results were scattered for SC-15 resin based system. Furthermore, core-shell dicyclopentadiene (DCPD)/PAN nanofibers mats were fabricated by coelectrospinning, which were inserted between carbon fabrics and formed the ultrathin self-repairing interlayers after resin infusion and curing. Three-point bending tests showed up to 100% recovery of the flexural stiffness of pre-damaged composite specimens by the core-shell nanofibers. The research demonstrated novel high-strength, self-healing lightweight structural composites for broad applications.