Piezoelectric materials have been widely used to harvest energy from ocean waves. This review is to introduce and review the development of the technologies. First, from comparison of the three major energy conversion techniques namely electrostatic, electromagnetic and piezoelectric technologies, in terms of power generation capability, transmission efficiency, and structural installation and economic costs, the advantages of applying piezoelectric energy conversion technology are identified. Second, the review sums up different methodologies and designs of harvesting energy from ocean waves based on different piezoelectric effects. In particular, the designs and efficiencies of available harvesters based on the piezoelectric effects from longitudinal, bending, and shear couplings are introduced and discussed. Finally, the futuristic research directions and methods for improving the efficiencies of the piezoelectric harvesters are discussed profoundly in this area.