This review investigates the role of vortex-induced vibrations (VIVs) in hydrokinetic energy harnessing, shedding light on their dual nature as both a challenge in offshore engineering and an untapped resource for renewable energy. VIVs serve as a novel energy source, converting the kinetic energy of fluid flows into mechanical or electrical power. The review discusses the various energy conversion mechanisms, highlighting the unique benefits and challenges of electromagnetic, piezoelectric, and triboelectric systems. A significant emphasis is placed on optimizing VIV energy harnessing to balance maximizing energy output while maintaining structural stability. The review provides insights into the geometric configurations, material properties, and advanced computational methods that are pivotal in this optimisation process. In conclusion, this review provides a comprehensive analysis of the current progress and persistent challenges in VIV research, offering actionable insights and innovative solutions that will advance the field of efficient and sustainable energy.