An organic light-emitting display apparatus includes a substrate, a pixel electrode disposed on the substrate, an opposing electrode disposed on the pixel electrode and transmitting light therethrough, an organic light-emitting layer disposed between the pixel electrode and the opposing electrode and emitting light toward at least the opposing electrode, a first transmission layer disposed on the opposing electrode and transmitting the light emitted from the organic light-emitting layer therethrough, and a second transmission layer disposed on a path of the light emitted from the organic light-emitting layer on the first transmission layer, and comprising a plurality of first materials having first refractive indices and a second material having a second refractive index. The first refractive indices are greater than the second refractive index, and the plurality of first materials are disposed inside the second material.