Current ocean wave observation is achieved by separate battery-powered sensing and signal transmission modules. Owing to the limited electrical supply and information channel space, the long-time span observation is restricted and only wave height and period information rather than the whole wave profile are sent back to the receiver. In this work, a self-powered ocean wave observation system was achieved by a developed polymer network liquid crystal (PNLC)-based smart reflector powered by a tailored triboelectric nanogenerator embedded with one-way overrunning clutches. The off-shore smart reflector modulated the on-shore emitted laser light, where ocean wave motion information can be revealed from the remotely detected reflected laser light without cable connections. The ocean wave rise and fall are distinguished by the developed one-way overrunning clutch, which selects the TENG to power the PNLC. Through the developed paradigm, ocean wave sensing and signal transmission can be achieved simultaneously, which is fully self-powered and free-of-cable. The flume-based self-powered ocean observation was performed with demonstrated wave height and period sensing accuracies of 92.66 and 97.32%, respectively.