A light guide plate includes a plate body and a supporting unit. The plate body has a light-exiting face and a lateral side, wherein the supporting unit is disposed along the lateral side. The supporting unit has a top surface and an outer lateral surface, the top surface is above the light-exiting face, the lateral surface protrudes from an end surface of the lateral side of the plate body, wherein a portion of the end surface away from the light-exiting face is exposed to form a recess. A backlight module includes the light guide plate mentioned above and a back plate having the light guide plate disposed thereon. A periphery of the back plate has a side wall formed thereon and extending into the recess. A display device includes the above light guide plate and a display panel.