This paper presents a high-sensitivity hydrophone fabricated with a Microelectromechanical Systems (MEMS) process using epitaxial thin films grown on silicon wafers. The evaluated resonant frequency was calculated through finite-element analysis (FEA). The hydrophone was designed, fabricated, and characterized by different measurements performed in a water tank, by using a pulsed sound technique with a sensitivity of −190 dB ± 2 dB for frequencies in the range 50–500 Hz. These results indicate the high-performance miniaturized acoustic devices, which can impact a variety of technological applications.