An organic light-emitting display apparatus includes a substrate, an organic light-emitting device including a first electrode disposed on the substrate, a second electrode disposed opposite the first electrode, and an intermediate layer disposed between the first and second electrodes, where the intermediate layer includes an organic emission layer, and an encapsulation unit disposed on the organic light-emitting device, where at least one of the substrate and the encapsulation unit, which is disposed in an emission direction of light, includes a region having a first refractive index and a region having a second refractive index greater than the first refractive index, and the region having the first refractive index and the region having the second refractive index include materials having a same chemical formula as each other.