The process for making a multi-layer panel consists of applying a first (3) and second (4) fibre-based material on the opposite faces of a core (2) of the panel (1), joining the first and second material through a needling operation through the thickness of the core, carrying out the impregnation of the first and second fibre-based material with a resin-based material and introducing the resin-based material inside the needling holes (6) for their entire extension, and polymerising the resin-based material so that at least the polymerised resin-based material present in the needling holes defines a plurality of structural rigidifying elements (5) that connect the first and second fibre-based material.