The present invention provides a water electrolysis electrode including a catalyst having a three-dimensional nanosheet structure with a low overvoltage and excellent catalytic activity, a method for producing the same, and a water electrolysis device including the same. The water electrolysis electrode according to the present invention includes a catalyst layer, which includes a composite metal oxide and has a three-dimensional nanosheet structure, and an electrode substrate. The method for producing a water electrolysis electrode according to the present invention comprises steps of: immersing an electrode substrate in an electrolyte solution containing metal oxide precursors; electrodepositing composite metal hydroxides by applying a voltage to the electrode substrate; and forming a composite metal oxide by annealing the electrode substrate. The water electrolysis device according to the present invention includes the water electrolysis electrode according to the present invention as an anode.