A method for forming a three-dimensional object uses a three-dimensional object printer to form a printed part and an injection molding system is used to form a molded part that adjoins the printed part and completes the three-dimensional object formation. The method includes operating an ejector head of a three-dimensional object printer to eject drops of material onto a platen to form the printed part, operating an actuator to move the printed part from the platen to a cavity of an injection mold of an injection molding system, and operating injectors of the injection molding system to inject material into the cavity of the injection mold to form the molded part that adjoins the printed part to form the three-dimensional object.