An OLED and a method of fabricating the same are provided, in which, when a reflective layer pattern is formed, a thin layer for a pixel electrode is opened at an edge of an emission region to form the pixel electrode without additional photolithography and etching processes by forming an undercut under the edge of the reflective layer pattern, i.e., under the edge of the emission region by over-etching, thereby simplifying the process and increasing the yield.