The multiphysics system integration and modeling method, including hydrodynamic, kinematic, and electromechanical models, were developed. A one-way plucking-driven piezoelectric wave energy harvester (OPD-PWEH) was also developed; it consists of a floating cylindrical buoy, a frequency up-conversion mechanism based on a one-way bearing, and a piezoelectric component based on an array of piezoelectric bulk composite cantilever beams. The one-way bearing converts the repetitive clockwise and counterclockwise rotary motion of the input shaft into a single-directional clockwise rotary motion of the output shaft. The OPD-PWEH was tested in a wave flume under wave amplitudes of 50, 37.5, and 25 mm and wave periods of 1.0, 1.5, and 2.0 s. The experimental results showed that the RMS voltage and average power were 4.47 V and 0.4 mW, respectively, and they were obtained at 50 mm wave amplitude and 1 s wave period.