Self-supported and flexible highly porous carbon nanofibers (HPCNFs) were prepared by electrospinning method combined with a post-two-step carbonization process. By introduction of air into the Ar flow during carbonization, carbon nanofibers were partially burnt off and a large number of micro/mesopores were created. As effective lithium storage units, the porous structure plays an important role in enhancing the electrochemical performances. The HPCNFs delivers a reversible capacity as high as 1780mAhg−1 after 40 cycles at 50mAg−1 and ultralong cycle life (1550mAhg−1 after 600 cycles at 500mAg−1). Even cycled at 25Ag−1, it still displays a very high capacity of 200mAhg−1. The outstanding electrochemical and mechanical properties of HPCNFs are attributed to the novel structure: pores provide good access of the electrolyte to the electrode surface and facilitate fast charge transfer across the electrode/electrolyte interface. 3D interconnected networks decrease the contact resistance and improve electrical conductivity of the overall electrode, which enhance electron transport rate. Therefore, this novel carbon material holds great promise for potential applications in energy-related technological and flexible electrodes for next generation LIBs.