A microelectromechanical mirror device has a fixed structure defining a cavity. A tiltable structure carrying a reflecting surface is elastically suspended above the cavity with a main extension in a horizontal plane. Elastic elements are coupled to the tiltable structure and at least one first pair of driving arms, which carry respective regions of piezoelectric material, are biasable to cause rotation of the tiltable structure about at least one first axis of rotation parallel to a first horizontal axis of the horizontal plane. The driving arms are elastically coupled to the tiltable structure on opposite sides of the first axis of rotation and are interposed between the tiltable structure and the fixed structure. The driving arms have a thickness, along an orthogonal axis transverse to the horizontal plane, smaller than a thickness of at least some of the elastic elements coupled to the tiltable structure.