A modular canopy assembly for enclosing a bed of a truck includes a frame and a set of panels. The frame comprises a set of first elements and a set of second elements. The first elements are mountable to a bed of a truck. The second elements are selectively engageable to the set of first elements so that the frame extends upwardly from the bed of the truck. The frame defines a top opening, a front opening, a rear opening, and opposed side openings. Each panel is selectively engageable to the frame to close a respective one of the top opening, the front opening, the rear opening, and the opposed side openings. The panels can be engaged to the frame to selectively enclose the bed of the truck.