A display apparatus is provided. The display apparatus includes a display panel, a backlight, a sensor, and a processor configured to drive the backlight unit so as to provide the display panel with light. The processor acquires a current duty for driving the backlight unit based on pixel information on an input image, acquires a gain value of the current duty based on ambient illumination sensed by the sensor and a ratio of a black pixel value included in the input image, and drives the backlight unit by applying the acquired gain value to the current duty.