Offshore renewable energy represents a crucial frontier in the global transition toward sustainable and low-carbon energy systems. With vast untapped potential in ocean resources, innovations in floating wind turbines, wave energy conversion technologies, and smart grid integration are reshaping the engineering landscape of offshore power generation. Floating wind turbines enable the deployment of large-scale wind farms in deep waters, while wave energy devices capture the kinetic and potential energy of ocean waves. Smart grid technologies provide the digital infrastructure necessary to efficiently integrate these variable resources into national and transnational power systems. This paper explores the engineering breakthroughs, challenges, and opportunities across these domains. Technical considerations such as structural design, energy storage, grid stability, and environmental impacts are examined, alongside policy frameworks and future research directions. Together, these innovations highlight the transformative potential of offshore renewable energy in achieving global sustainability and energy security.