Joining materials with different physicochemical properties presents significant challenges. This study investigates the one-step anodization of aluminum in a mixed phosphoric acid and hydrogen peroxide solution, followed by direct injection molding of polymer resin to enhance joint properties. Furthermore, three-dimensional (3D) printing process was able to join polymer resins to the anodized aluminum surface. This alternative approach addresses the environmental issues associated with the use of Cr(VI)-based anodizing solutions and the lightweight composites with applicability to various industries could be produced using this method.