Thermal conductivity of individual polyvinylpyrrolidone (PVP) nanofibers embedding boron nitride nanotube (BNNT) fillers has been measured. The PVP nanofibers were electrospun on suspended microdevices in order to better understand the effect of BNNT fillers on the thermal conductivity of polymeric nanofibers. Various material characterization methods provided evidence that ketone group in the PVP interacted with the surface of BNNTs via strong intermolecular forces, thereby resulting in an effective heat transfer between the polymer matrix and BNNTs. The individual PVP nanofiber containing 30 wt % of BNNTs exhibited approximately 2-fold higher thermal conductivity than that of the bulk PVP.