Hybrid carbon nanofibers (NFs) with extremely high Si loading (> 65 wt%) are fabricated through the water-based electrospinning of polyvinyl alcohol/Si nanoparticle (NP) solutions for Li-ion battery anode applications. Our Si-rich carbon (SRC) NFs show many facilitated charge-transport features and increased activities because of the continuous one-dimensional (1D) carbon backbone structure with dispersed Si NP domains. This leads to superior battery performance compared to that of bare silicon NPs. The presence of carbon as 1D NFs can not only mitigate the volume change of silicon but also avoid the formation of an unstable solid-electrolyte interface on the surface of silicon. Our study, regarding the optimum combination of C and Si in the NFs for their improved electrochemical properties and battery performance, reveals that SRC NFs containing 72.8 wt% Si (27.2 wt% C) exhibit an adequate balance between the high energy capacity of Si NPs and the dimensional stability and effective charge transport of carbon NFs. This optimum Si/C ratio leads to an outstanding cycle life, which maintains 1076 mAhg(-1) capacity normalized by the total electrode mass, and a Coulombic efficiency of about 99% over 50 cycles. Such scalable SRC NFs produced through the water-based spinning approach can offer a cost-effective development for high-performance battery anodes.