We report a simple solution route to large-scale synthesis of uniform, single-crystalline, and well-faceted orthorhombic antimony trioxide (Sb2O3) nanowires with rectangular cross sections by direct air oxidation of bulk metal antimony (Sb) in a mixed solution made of ethylenediamine (EDA) and deionized water (DIW). The as-synthesized products were analyzed by range of methods, such as XRD, SEM, EDX, TEM, SAED, HRTEM, FTIR, Raman, UV-vis absorption, and photoluminescence (PL) spectra. The as-synthesized Sb2O3 nanowires with rectangular cross sections are usually hundreds of micrometers in length, typically 80-100 nm in width, and 60-80 nm in thickness. The novel room temperature photoluminescence properties of Sb2O3 nanowires with rectangular cross sections displayed a significant UV luminescence with a strong emission band at 374 nm, which was reported for the first time, indicating the as-synthesized products with an optical band gap E-g = 3.3 eV. It is expected that as-synthesized Sb2O3 nanowires would be a new member of functional materials and used in the manufacture of advanced nanodevices.