Abstract: A thin, pliable, self-adhesive corner reinforcement for cardboard boxes. Two adjacent side panels are pivotally connected by a narrow vertical crease which affords a bending capability without fracture. Each of the side panels is pivotally connected to a base flap by a narrow horizontal crease extending the width of each side panel to allow a non-fracturing bending capability. The outer and inner edges of the base flaps are trimmed directionally toward each other to form a triangular shape while the apex of each triangle is bevelled and the corner formed at the right angle in the outer upper quadrant of each side panel is also bevelled. An adhesive covers the reinforcement in its entirety on one side. A peel-off strip covers the adhesive to prevent premature adhesion and has cut lines at the vertical and horizontal creases of the reinforcement to facilitate singular removal and ease of application.