Modular cover (100, 200, 300, 400) for electronic devices (50), comprising: - a covering and protecting element (101, 201, 301, 401) having an external rear surface (101a, 201a, 301a, 401a), removably housing an electronic device (50); - and a
system for adjusting the dimensions of said covering and protecting element (101, 201, 301, 401). The modular cover (100, 200, 300, 400) comprises also at least one
functional module, comprising an electronic
processing unit, removably mounted on the external rear surface (101a, 201a, 301a, 401a) of the covering and protecting element (101, 201, 301, 401). The
system for adjusting the dimensions of the covering and protecting element (101, 201, 301, 401) comprises a plurality of sliding arms and a plurality of interchangeable
peripheral edges, where each interchangeable
peripheral edge is removably connected to one end of a corresponding sliding arm.