We have developed a priority-related chemical etching method to transfer the starting Pt–Ni polyhedron to a nanoframe. Utilizing the lower electronegativity of Ni in comparison to Au atoms, in conjunction with the galvanic replacement of catalytically active Au to Ni tops, a unique Au island on a Pt–Ni trimetallic nanoframe is achieved. The design strategy is based on the structural priority mechanism of multimetallic nanocrystals during the synthesis and thus can be generalized to other analogous metal–bimetallic nanocrystal combinations (such as Pd and Cu islands on Pt–Ni nanoframes), which is expected to pave the way for the future development of efficient catalysts.