Bi is a promising candidate for energy storage materials because of its high volumetric capacity, stability in moisture/air, and facile preparation. In this study, the electrochemical performance of nanosized-Bi-embedded one-dimensional (1D) carbon nanofibers (Bi/C nanofibers) as anodes for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) was systematically investigated. The Bi/C nanofibers were prepared using a single-nozzle electrospinning method with a specified Bi source followed by carbothermal reduction. Abundant Bi nanoparticles with diameters of approximately 20 nm were homogeneously dispersed and embedded in the 1D carbon nanofibers, as confirmed by structural and morphological characterization. Electrochemical measurements indicate that the Bi/C nanofiber anodes could deliver a long cycle life for LIBs and a preferable rate performance for NIBs. The superior electrochemical performances of the Bi/C nanofiber anodes are attributed to the 1D carbon nanofiber structure and uniform distribution of Bi nanoparticles embedded in the carbon matrix. This unique embedded structure provides a favorable electron carrier and buffering matrix for the effective release of mechanical stress caused by volume change and prevents the aggregation of Bi nanoparticles.