Hierarchically ZnIn2S4 nanosheet-constructed microwire arrays (NCMAs) on a zinc substrate have been synthesized for the first time through a one-step solvothermal method without using any template or surfactant. The as-synthesized ZnIn2S4 microwires are constructed by vertical nanosheets preferentially exposing (006) facets, which are about 1-5 μm in diameters and larger than 10 μm in average length. Experimental results demonstrate that the hierarchically ZnIn2S4 NCMAs are converted from intermediate components of single crystalline indium nanowires, which are generated along the direction of (101) planes by a displacement reaction between Zn and In3+ during the initial synthesis process. This conversion of indium nanowires to hierarchically ZnIn2S4 NCMAs has been explained by a novel corrosion-exchange-self-assembly mechanism, which might indicate a novel strategy for preparing other ternary sulphide nano-microwire arrays. The prepared ZnIn2S4 NCMAs are used as photocatalysts, demonstrating effective photocatalytic degradation activity for diverse organic pollutants including different dyes, tetracycline and 2,4,6-tribromophenol (2,4,6-TBP). This efficient photocatalytic activity is ascribed to the strong absorption of ZnIn2S4 NCMAs in a wide range from ultraviolet to visible light as well as the preferentially exposed (006) facets of ZnIn2S4 nanosheets.