Provided is an electrocatalyst for anion exchange membrane water electrolysis, including a carbonaceous material, and nickel electrodeposited on the carbonaceous material, wherein nickel is partially substituted with platinum and the substitution with platinum provides increased hydrogen evolution activity as compared to the same electrocatalyst before substitution with platinum. Also provided are a method for preparing the electrocatalyst and an anion exchange membrane water electrolyzer using the same. The nickel electrocatalyst coated with an ultralow loading amount of platinum for anion exchange membrane water electrolysis shows excellent hydrogen evolution activity and has a small thickness of catalyst, thereby providing high mass transfer and high catalyst availability. In addition, the electrocatalyst uses a particle-type electrode to facilitate emission of hydrogen bubbles generated during hydrogen evolution reaction and oxygen bubbles generated during oxygen evolution reaction, and requires low cost for preparation to provide high cost-efficiency.