Harvesting energy from ocean wave is a promising renewable energy source due to its high efficiency, carbon-free, it is not affected by depletion of fossil fuels, and it is replenished constantly. The existing generators used in wave energy harvesting such as linear generator and slider crank mechanism have some limitations, which include lower efficiency and technologically challenging. Thus, in this work, wave energy harvesting technique using rotational generator based on scotch yoke mechanism is proposed. A typical slider crank to convert linear motion into rotational motion is replaced by scotch yoke mechanism to yield higher efficiency. A comparison of the performance of wave energy system between employing slider crank and scotch yoke is made to evaluate the superiority of the proposed mechanism. From the results obtained in this work, it is found that the output voltage of rotational generator employing scotch yoke mechanism is higher compared to that of rotational generator employing slider crank for the same input power. Thus, rotational generator by employing scotch yoke mechanism can be one of the alternative methods for ocean wave energy harvesting.