An organic light emitting device and a method of manufacturing the same are provided. The organic light emitting device, from bottom to top, includes a substrate, an indium tin oxide layer, a semiconductor layer, and a pixel defining layer. The semiconductor layer covers foreign particles on the indium tin oxide layer to make the indium tin oxide layer have an even thickness. The method of manufacturing the organic light emitting device including steps of providing an indium tin oxide layer, providing a semiconductor layer, patterning, and providing a pixel defining layer. The disclosure prevents from uneven brightness (mura) causing from a bright spot or a dark spot appearing at the foreign particles and ensures an overall even brightness of the organic light emitting device by providing the semiconductor layer disposed on the indium tin oxide layer to cover foreign particles on the indium tin oxide layer.