A backlight unit, a display device including the backlight unit, and a method of manufacturing the display device. The backlight unit includes: a bottom chassis having one or more through holes; and a reflective sheet disposed on the bottom chassis and including a flat portion having a flat surface and an inclined portion connected to the flat portion to form an inclined surface. The inclined portion of the reflective sheet is at least partially inserted into each of the through holes of the bottom chassis.