Nanocantilever arrays were formed on the edges of the +/-(0001) planes of pre-synthesized ZnS nanoribbons via catalyst-assisted post-annealing treatment on Si substrate at 600 degrees C. Similar nanostructures could also be generated when ZnS nanoribbons were annealed by mixing with Si or SiO powder. The formation of nanocantilever arrays is associated with orientation-dependent chemical etching of the (0001) polar surfaces of ZnS nanoribbons. The ability of increasing structural complexity beyond the one-step "thermal evaporation and condensation" synthesis provides a new dimension to the rational design of building blocks for nanodevices.