A microelectromechanical system (MEMS) electric-field sensor (EFS) is presented in which the ambient electric field (E-Field) is modulated by vertical electrode displacement using lead-zirconate-titanate (PZT) piezoelectric actuators. The device is fabricated with a multi-layer copper-on-PZT process, which enables large (~10 μm) displacement and high aspect ratio electrode structures as needed for sensitive detection. The modulated displacement current between two electrodes, measured using a transimpedance amplifier, is proportional to the ambient, sensed E-Field. Fabricated EFS devices yielded a responsivity of 830 fA/(V/m) and a limit of detection down to 0.19 V/m/rtHz in vacuum (0.30 V/m/rtHz in air) with a 491-Hz E-field applied.