A multi-functional clamp for the installation of a wind turbine on an offshore substructure by a crane vessel equipped with a lifting crane, the multi-functional clamp having: a main body configured to selectively clamp and unclamp the lower part of the tower of a wind turbine and is shaped so as to couple with the crane vessel so as to define a given position for the tower with respect to the crane vessel; and a plurality of hooking members extending from the main body and configured to secure and release the free ends of a rigging assembly of the lifting crane to the main body so as to lift the multi-functional clamp by the lifting crane.