We herein report that spherical and sheetlike Ag/AgCl nanostructures could be controllably synthesized by means of chemical reactions between AgNO3 and cetyltrimethylammonium chloride (CTAC) surfactant. In this synthesis system, AgNO3 works as the silver source, while CTAC serves not only as the chlorine source but also as the directing reagent for a controllable nanofabrication. We show that compared to the spherical Ag/AgCl nanostructures, the sheetlike counterparts, wherein the AgCl nanospecies are predominantly enriched with {111} facets, could exhibit superior catalytic performances toward the photodegradation of methyl orange. Interestingly, we further demonstrate that when 4-chlorophenol or phenol is used as the substrate, the sheetlike Ag/AgCl nanostructures exhibit inferior catalytic reactivity, whereas the spherical counterparts display superior catalytic performances comparatively. Our results disclose new insights on the facet-dependent catalytic performances with regard to a facet-selective but substrate-sensitive photoinduced electron-hole separation.