A multi-layer prefabricated wall panel for modular building and a method for manufacturing the same. The panel comprises a load-bearing and vapor barrier core layer; an interior insulating and utility installation layer bonded to the inner face of the core layer; an exterior sheet of a first rigid building material bonded to the interior insulating layer; and an interior sheet of a second building material bonded to the outer face of said core layer. The method for manufacturing the wall panel comprises the steps of forming a stack of the panel layers with adhesive coating between successive layers and bonding the layers to each other by uniform compressing forces.