A MEMS sensor device provided with a sensing structure, having: a substrate with a top surface extending in a horizontal plane; an inertial mass, suspended over the substrate; elastic coupling elements, elastically connected to the inertial mass so as to enable inertial movement thereof with respect to the substrate as a function of a quantity to be detected along a sensing axis belonging to the horizontal plane; and sensing electrodes, capacitively coupled to the inertial mass so as to form at least one sensing capacitor, a value of capacitance of which is indicative of the quantity to be detected. The sensing structure moreover has a suspension structure, to which the sensing electrodes are rigidly coupled, and to which the inertial mass is elastically coupled through the elastic coupling elements; the suspension structure is connected to an anchorage structure, fixed with respect to the substrate, by means of elastic suspension elements.