Carbon nanofibrous nonwoven mats (CNFMs) prepared via electrospinning offer excellent electrical and structural properties and have been used as frameworks for electrodes in electrochemical energy storage devices. However, lack of mechanical strength hinders the broad applications of CNFMs in flexible electronics or industry use. In this work, a rapid stabilization method is developed to prepare high-strength and flexible CNFMs. Studies of the effects of stabilization time on the structures of the stabilized polyacrylonitrile (PAN) nanofibers and the subsequent carbon nanofibers reveal that there is an optimal stabilization time for making high-strength CNFMs. Long stabilization time results in excessive oxidation of the stabilized PAN nanofibers and unwanted defects in the carbon nanofibers. Short stabilization time results in carbon nanofibers with less crystalline structures due to insufficient formation of the thermally stable ladder-like structure. Robust and flexible CNFM with the highest tensile strength of 192.7MPa is obtained using an optimized total stabilization time of 40min. To demonstrate the application of the flexible CNFMs, they are fabricated as an electrode framework to load TiO2 nanoparticles without use of organic binders. Lithium ion half-cell based on this electrode demonstrates superior rate cycling performance owning to the porous structure and highly conductive fibrous carbon network of CNFM.