In an organic light-emitting display device and a method of manufacturing the same, the organic light-emitting display device includes: a silicon layer formed on a substrate; and a thin film transistor (TFT) and an organic light-emitting device that are formed on the silicon layer. The silicon layer comprises a conductive doping silicon portion for forming a part of an active layer included in the TFT and an insulating intrinsic silicon portion surrounding the doping silicon portion. According to the organic light-emitting display device of the present invention, manufacturing costs may be reduced due to a reduction in the number of masks, and the manufacturing process of the organic light-emitting display device may be simplified.