The simultaneous enhancement of magnetic and ferroelectric properties of one-dimensional nanostructured bismuth ferrite (BiFeO3) is highly desired due to their potential applications in nanoscale devices, such as multistate memory device and micro-magnetoelectric sensor. Sm-doped BiFeO3 nanofibers were synthesized by a sol-gel-based electrospinning process. The as-fabricated nanofibers show significantly enhanced magnetization due to the suppressed periodic spin cycloid and the uncompensated surface spins. The magnetization of Bi0.90Sm0.10FeO3 nanofibers is nearly twice as much as that of the nanoparticles at the same doping level. More importantly, Sm-doped BiFeO3 nanofibers hold the higher dielectric constant and stronger DC bias-dependent dielectric constant due to the enhanced polarization by Sm doping. Temperature-dependent dielectric constant and dissipation factor suggest that the dielectric properties of Sm-doped BiFeO3 nanofibers remain stable below 250 degrees C, providing a wide temperature range for applications in memory devices or sensors. The tuning of magnetic and ferroelectric properties of the Sm-doped BiFeO3 nanofibers appears to be very promising for achieving multifunctionality in a single material.