In this paper, we present design, modeling analysis, and experimental study of a vibration-based energy harvester. The energy harvester is made of a composite cantilever of a single crystal relaxor ferroelectric material (PMN-PT), and a polydimethyl-siloxane (PDMS) base layer. A PDMS proof mass is constructed at the tip of the composite cantilever beam. The use of the PMN-PT piezo-material and an interdigited electrodes (IDE) design improves the energy conversion efficiency. The PDMS base layer prevents the possible damage to the fragile PMN-PT layer. A dynamic systems approach is employed to analyze the responses and the performance of the harvester design. The experiments have demonstrated that a prototype of the harvester with a size of 7.4 mm × 2 mm × 110 μm can produce a maximum output voltage of 10 V (0.3 mW power) under a vibration excitation with a peak-to-peak amplitude of 1 mm, and the power density can reach 4.15 mW/cm3 under short circuit conditions.