Abstract: A collapsible storage unit for a truck for providing a collapsible storage container for truck boxes. The collapsible storage unit for a truck includes a storage assembly including a box-like storage member having a bottom wall, a back wall being hingedly attached to the bottom wall, side walls being hingedly attached to the bottom wall, a front wall being hingedly attached to the bottom wall, and a lid being hingedly attached to the back wall with the side walls being removably fastened to the front and back walls; and also includes a hinge assembly for fastening the walls together to form the box-like storage member; and further includes a storage member securement assembly for securing the box-like storage member to side walls of a truck box.