Bright single‐layer white light‐emitting organic electroluminescent devices were developed by using dye‐dispersed poly(N‐vinylcarbazole) (PVK). The active layer consists only of one polymer layer that is simply sandwiched between two electrodes, indium‐tin oxide, and Mg:Ag. In order to achieve bipolarity in the single polymer emitter layer, PVK was molecularly dispersed with electron‐transporting additives such as 2‐(4‐biphenyl)‐5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole. In addition, several fluorescent dyes, having different emission colors, were dispersed as emitting centers. By adjusting the concentration of the fluorescent dyes, white light with a maximum luminescence of 4100 cd/m2 was obtained, which is the brightest white light ever observed for organic electroluminescent devices.