This work examines the roles played by wall thickness in determining the plasmonic properties of gold-silver (Ag-Au) nanocages. Ag-Au cages with different wall thicknesses, but the same void or outer size, shape, and elemental composition, were designed as a model platform. The experimental findings were understood with theoretical calculations. This study not only investigates the effect of wall thickness but also provides an effective knob to tailor the plasmonic properties of hollow nanostructures.