© 2020, The Author(s). Electrochemical water splitting driven by renewable energy-derived electricity is considered as the most promising pathway for delivering clean and sustainable hydrogen production. The key to achieving an efficient water splitting process is developing highly active electrocatalysts. Two-dimensional (2D) nanomaterials hold great promise in the electrocatalysis field due to their unique physicochemical properties. Some of them are not active enough because of the poor intrinsic activity, low density of active sites or low electrical conductivity. Some are inert for electrocatalytic reactions, but are able to work as the functional substrates for hybrid electrocatalysts. Thus, tremendous strategies have been developed to modulate the physicochemical and electronic properties of 2D nanomaterial-based electrocatalysts, and to make full use of the functionalities of functional 2D nanomaterial substrates to achieve fast catalytic reaction kinetics. In this review, the recent progress on the well-established design strategies for the 2D nanomaterials-based electrocatalysts is highlighted. The perspectives on the current challenges and future development of 2D electrocatalysts are addressed.