An organic light emitting display and power supply method thereof operate an organic light emitting display panel using a high voltage EVLDD and a low voltage ELVSS supplied from a driver integrated circuit during a low power display mode. The organic light emitting display a first power supply configured to supply a first power including a first high voltage and a first low voltage, a second power supply configured to supply a second power including a second high voltage and a second low voltage, and an organic light emitting display panel configured to receive the first power from the first power supply in a standard display mode and configured to receive the second power from the second power supply in a low power display mode.