The truck bed extender (10) has three panels (12, 26a, 26b) removably attached to the edge of the vehicle tailgate (G) and the rear portions (LR, RR) of the cargo box sidewalls (LW, RW). The deployed extender (10) increases the vehicle capacity and efficiency. The side panels (26a, 26b) fold against the inner surface of the primary panel (12) and the primary panel (12) folds against the inner surface of the tailgate (G) for compact storage of the assembly. The panel assembly (10) may be quickly and easily removed from the permanently installed hinges (14a, 14b) on the vehicle tailgate (G). The extender assembly (10) may be deployed, stored, removed, and installed without tools, once the primary panel hinges (14a, 14b) and side panel attachment brackets have been installed on the vehicle.