The marine buoys are subjected to aggressive dynamic loads. One of the recently invented effective tools for suppressing the negative impact of these loads is the energy harvesting devices. The proposed energy harvester consists of two main components: tuned mass damper and electricity generator. The innovative component of that energy harvester is specifically designed tuned mass damper springing element having a possibility to be automatically adjusted to variable external force frequency. The wave energy harvesting buoy is a prototype for demonstration of all steps of energy harvesting technology implementation into the buoy’s practice.