This document describes techniques and apparatuses for implementing an object-detecting backlight unit for a display device. An object-detecting backlight unit includes two or more light sources configured to provide light to a display to form an image, and a light sensor configured to receive reflected light when an object is near the display and determine that the reflected light originated from a region of the display. The reflected light is caused by light from the image reflecting off of the object back towards the display. The backlight unit is configured to detect a position of the object based on the region of the display from which the reflected light originated.