An organic light-emitting display device and a method of manufacturing the same are disclosed. The organic light-emitting display device includes: a lower substrate including a display area and a non-display area, the lower substrate further including a power supply wiring unit disposed in the non-display area, the power supply wiring unit including at least one power supply wiring extending along an edge of the display area; an encapsulation substrate having an outer surface and an inner surface facing the lower substrate; a cavity formed into the inner surface of the encapsulation substrate in a region over the power supply wiring unit such that the cavity overlaps at least part of the power supply wiring when viewed in a direction perpendicular to the outer surface of the encapsulation substrate; and a polarizing plate disposed on the outer surface of the encapsulation substrate.