A light-emitting device is provided. The light-emitting device comprises a light-emitting stack comprising a first semiconductor layer, a second semiconductor layer and an active layer between the first semiconductor layer and the second semiconductor layer. The light-emitting device further comprises a third semiconductor layer on the light-emitting stack and comprising a first sub-layer, a second sub-layer and a roughened surface, wherein the first sub-layer has the same composition as that of the second sub-layer, and the composition of the first sub-layer is with a different atomic ratio from that of the second sub-layer. A method for manufacturing the light-emitting device is also provided.