Materials with Janus structures have attracted significant attention in recent years. Here, we fabricated a novel type of Janus ultrafine fiber membrane (UFM) by designing a spinneret via electrospinning and polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) Janus ultrafine fibers were successfully obtained at a large scale. The morphology, chemical composition, and solubility of the PAN/PVP Janus UFM in water were studied in detail via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR). Compared to a PAN/PVP composite UFM, the Janus UFM exhibited significant self-supporting properties when the PVP side was dissolved in water, which was attributed to the PAN side still maintaining the required net structure. Two fluorescent molecules were added to the Janus UFM to enable further characterization. The applicability of this PAN/PVP Janus UFM as a drug carrier was investigated. The results indicated ideal biphasic drug release features in the Janus UFM and that the addition of fluorescent dyes can be used to track the process of drug release. The good self-supporting properties and the biphasic drug release feature indicate the broad applicability of the PAN/PVP Janus UFM.