We demonstrated highly efficient OLEDs by incorporating ZnS nanodots on top of a glass substrate via a chemical bath deposition process. The device efficiency of OLEDs with ZnS nanodot arrays was 1.26times higher than that of OLEDs without ZnS. This enhancement in device efficiency is attributed to the improved light out-coupling efficiency that is enabled by the improved optical performance of nanodot arrays, which results from their high refractive index and optical transmittance in the visible wavelength.