Wave energy is still mostly unexploited because it is challenging to reach high energy density and commercial viability. In this paper, we present a novel power take-off (PTO) system based on dielectric elastomer generators (DEGs), which has the potential to tackle these challenges. The major difference to previous research on DEGs for ocean energy is that we intentionally use the elastic properties of the DEG to match the dynamic response of the complete device to the excitation spectrum. Wave energy converters (WEC) require breakthroughs for the PTO to convert the translational motion of waves into electric energy and to operate in the system’s resonance at the low-frequency wave excitation for high power absorption. A low-cost DEG-PTO with high energy density is built upon the research of the past decade and could solve both challenges simultaneously, increase the resonance period of the WEC and efficiently convert wave energy into electric energy at the same time. The DEG is stretched by a novel mechanism that makes use of the so called “negative stiffness” effect. This allows the WEC to increase its resonance period to match the wave’s period and show a broadband dynamic response. The paper deals with the modelling and numerical performance assessment of the DEG-PTO. Results obtained by an experimental test bench for hardware-in-the-loop (HIL) simulations validate the proposed approach. The developed DEG mechanism also has the potential for application in alternating lift technology to harvest tidal energy.