Water splitting powered by clean electricity is a sustainable and promising approach to produce green hydrogen. Currently, noble metal (e.g. Iridium, Ruthenium, Platinum)-based catalysts are most widely used for water splitting electrolysis. However, noble metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity and poor durability. The emergence of metal-organic framework nanosheets (MOFNSs) attracts significant attention due to their unique advantages. Here, a concise, yet comprehensive and critical, review of recent advances in the field of MOFNSs is provided. This review explains the fundamental oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic mechanisms as well as key characterization techniques for the structure-activity relationship study are discussed. Moreover, it discusses efficient design strategies and the brief research advances of MOFNSs in HER, OER, and bifunctional electrocatalysis, along with some challenges and opportunities.