Magnetic nanoring structures are attractive for spintronic devices due to their unique attributes of well-defined and reproducible magnetic states originating from their characteristic geometry. Almost all previous magnetic nanorings have been exclusively limited to traditional ferromagnetic materials, and a magnetic semiconductor (MSC) nanoring structure has been reported rarely during the past decades. Here, it is demonstrated that room-temperature ferromagnetic Ag1.2V3O8 nanobelts and nanorings may be achieved by controlled oxidation of the V4+ precursors in an Ag+-containing aqueous solution. The polarization-induced self-coiling of in situ formed Ag1.2V3O8 nanobelts is responsible for the formation of the perfectly circular nanoring geometry. The NEXAFS spectra and the density functional calculations clearly reveal that the electron transfer originates from the hybridization of the doped Ag+ and V4+ atoms, causing ordering of the magnetic moments that give rise to the intrinsic ferromagnetism of the Ag1.2V3O8 structure.