A MEMS optical device having an optically active portion and an actuation portion adjacent to each other. The MEMS optical device includes a body, a piezoelectric actuator, and a cap. The body is formed by a substrate, housing a cavity containing a fluid and by a deformable region fixed to the substrate, suspended over the cavity and forming a membrane. The piezoelectric actuator extends on the deformable region at the actuation portion and is protected by the cap, which is coupled to the body at the actuation portion and defines a chamber that houses the piezoelectric actuator.