A series of porous cubic nanomaterials have been prepared through a facile one-step selenylation process, in which Cu-Ni-Co, Ni-Co and Cu-Co Prussian-blue analog nanocubes transformed to Cu-Ni-CoSex, Ni-CoSex and Cu-CoSex nanocubes, respectively. Among these samples, the quaternary porous nanocubes (Cu-Ni-CoSex) proved to be the excellent bifunctional electrocatalysts in dye-sensitized solar cells and hydrogen evolution reactions. Under the standard irradiation, Cu-Ni-CoSex nanocubes exhibited a high power conversion efficiency of 9.74% in solar cells, which was much superior than that of N (8.19%). Cu-Ni-CoSex nanocubes also delivered superb hydrogen evolution performance in terms of a low overpotential (50.2 mV) under the current density of 10 mA cm(-2) and a low Tafel slope (49.6 mV dec(-1)) in alkaline medium. The outstanding characteristics of CuNi-CoSex nanocubes were benefited from their uniform sizes, porous morphologies, high surface area, low charge transfer resistances and good synergies among multiple elements.