A display control method and an apparatus for power saving of a display unit are provided. The method includes, determining a display mode in response to input of external illumination data, detecting input of a Red-Green-Blue-White (RGBW) data frame, applying a weight corresponding to the determined display mode to at least a White (W) sub-pixel value among pixel values of the RGBW data frame, determining luminance control data using the pixel values to which the weight is applied; and controlling the lighting system to output light based on the determined luminance control data, and controlling the display panel to transmit the light based on the determined luminance control data.