The present invention concerns a process for manufacturing facing panels in composite material (1) which can be applied to structural and not structural walls, to ceilings, to mobile or fixed surfaces, both inner and external of buildings, enclosures or other structures, mainly, but not exclusively, in home-building field or be used as separate and independent walls too. The invention further concerns the panel (1) built through this process. It allows to make decorative, facing and insulating panels (1) whose thickness changes according to the kind of material (3), which basically reproduce any natural materials, such as stone(s) (14), rock(s), marble, wood and not, for example bricks (15) or other finishes with random shapes at variable height differences (5) in plane or curved surfaces, reducing costs and laying time with great flexibility and easy of use.