Renewable energy technologies have been continuously improved as a result of the pressing need for sustainable energy. Among these, hydrogen energy has received widespread attention from scientific researchers because of its clean, eco-friendly, and high energy density. Electrocatalytic water splitting for hydrogen production, especially at high current densities (HCD), is seen as a key approach to reshape the global energy landscape and achieve carbon neutrality. Therefore, finding cost-effective electrocatalysts with excellent activity and stability under HCD is important for large scale water splitting. Layered double hydroxides (LDHs) are highly recognized as promising electrocatalysts due to their unique two-dimensional molecular layered structure, high structural regulability, and readily available raw materials. In this review, we outline the fundamental principles of water electrolysis in alkaline water/seawater environments, analyzing the necessity for catalysts in HCD designs. We then delve into innovative approaches of LDH electrocatalysts for HCD alkaline water splitting. Lastly, we present an overview of the challenges and opportunities associated with HCD alkaline seawater electrolysis.