An apparatus and a method for dynamic backlight-control in an electronic device are provided. The apparatus includes a battery power-level detection unit and a controlling unit. The battery power-level detection unit is used for detecting the power level of a battery in the electronic device. The controlling unit is coupled to a backlight unit of a display device in the electronic device and the battery power-level detection unit for adjusting the illumination of the backlight unit according to the power level of the battery and an image-content lightness of an image inputted into the display device.