Triboelectric nanogenerator (TENG) is a new cost-effective blue energy harvesting technology for its great performance in low frequency. However, many related energy harvesters operate on water surface, ignoring the ocean’s depth. Herein, a chain-flipped plate TENG (CFP-TENG), consisting of longitudinally arranged repeating units, is proposed to collect wave energy. The chain structure design allows the surface wave energy to act effectively on the underwater generator. The maximum output power per unit ocean area reaches 1.5 W·m⁻² at a loading resistance of 30 MΩ. Optimization of device parameters and application demonstrations are explored. Compared with previous works, the utilization rate of wave energy has been significantly improved. This work not only provides a new method to optimize the output of TENG but also makes a crucial step in promoting practical applications of TENG in renewable blue energy.