A truck bed guard is provided that includes an undulating protective panel having a plurality of longitudinally aligned bends that forms at least one groove and at least one protrusion configured to increase impact resistance. A first flange extends transversely from the top of the panel to provide a first attachment feature, and a second flange extends vertically down beneath the panel to provide a second attachment feature. The guard may be attached to a bed wall of a truck via the first attachment feature and the second attachment feature. A gap between the undulating protective panel and the bed wall is configured to prevent damage to the bed wall. The truck bed guard provides impact resistance to protect the bed wall from objects transported in the truck bed.