The global energy crisis and environmental concerns have prompted a search for alternative energy sources, with electrochemical overall water splitting emerging as a promising method for converting renewable energy’s electrical output into storable and transportable chemical fuels, mainly hydrogen and oxygen. The development of economic and highly active electrocatalysts for both H2 and O2 evolution processes is critical for industrial water splitting. Among them, two-dimensional (2D)-based electrocatalysts have gained tremendous attention in water splitting applications due to their special benefits like high surface area, activity, and stability, providing structural and functional design abilities. Additionally, these structures exhibit significant surface defects with impressive mass transport and fast electron transfer for boosting electrocatalytic activity. Special attention is paid to mechanisms of the overall water splitting process for the production of hydrogen with the help of 2D materials such as carbons, oxides, polymers, MXenes (carbides, nitrides, carbonitrides), chalcogenides, and metal-organic frameworks (MOFs). Future 2D-based materials design and development should involve a combination of theoretical calculations, electrochemical measurements, and advanced spectroscopic analysis. The goal of this chapter is to highlight the current state of 2D-based electrocatalyst development and possible applications, as well as important difficulties and opportunities for future electrochemical water splitting technologies.