High entropy alloys are considered one of the major breakthroughs in alloying concepts. Their unique design concept and mixed entropy effects make the materials potentially valuable in many applications in various fields. This Research Update summarizes recent research progress on high entropy alloy catalysts in electrolytic water splitting. The definition and properties of high entropy alloys are described and the common preparation methods and organizational characteristics of high entropy alloys are discussed. The catalytic effects of high entropy alloys in water electrolysis are evaluated, and finally, the future development trend and application prospects of high entropy alloys are outlined.