The invention relates to a method of fabricating a composite micromechanical component, particularly for timepiece movements, including steps: a) providing a substrate including a horizontal top layer and a horizontal bottom layer made of electrically conductive, micromachinable material, and secured to each other by an electrically insulating, horizontal, intermediate layer; b) etching a pattern in the top layer through to the intermediate layer, thereby forming at least one cavity in the substrate; c) coating the top part of the substrate with an electrically insulating coating; d) directionally etching the coating and the intermediate layer to limit the presence thereof exclusively at each vertical wall; e) performing an electrodeposition by connecting the electrode to the conductive bottom layer of the substrate to form at least one metal part of the component; g) releasing the composite component from the substrate.