A reinforced box for containing a plurality of items to be packaged includes a bottom wall and a top wall, a pair of first side walls and a pair of second side walls. The bottom wall, the top wall and the pair of first side walls are formed from a one-piece elongate element, which extends along a longitudinal axis and is formed with transverse fold lines. The pair of second side walls consists of two separate cardboard panels, and each of the walls is formed with longitudinal creasing lines defining pairs of first and second folded side wings. The pair of second side walls is glued to the bottom wall using a respective second side wing overlapping the bottom wall to reinforce its longitudinal edges. A method of making a box with a reinforced structure is also disclosed.