Double-shelled hollow structures possess unique properties in energy conversion/storage fields due to their higher surface area, larger contact region with the electrolyte and much shortened paths of charge transfer. In this work, CoMoSx@Ni-CoMoSx hollow polyhedron catalyst with a double-shelled cage-in-cage structure is prepared by a sequence of template-engaged synthetic processes. In the synthetic procedure, (NH4)(2)MoS4 is applied as a multifunctional vulcanizator, which can conveniently afford Mo and S elements at the same time. Noteworthily, by comparing with single-shelled hollow CoMoSx and Ni-CoMoSx polyhedrons, the double-shelled CoMoSx@Ni-CoMoSx polyhedron catalyst demonstrates superior catalytic properties in the reduction of triiodide in dye-sensitized solar cells. The solar cell with CoMoSx@Ni-CoMoSx based counter electrode exhibits a high power conversion efficiency of 9.30%, which is much higher than that of Pt (8.01%).