Novel mesoporous hollow‐flower‐ball‐like Cd4Cl3(OH)5 was selectively synthesized using microwave‐irradiation process. The structure of the resultant Cd4Cl3(OH)5 was characterized by scanning electron microscopy (SEM), X‐ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and low temperature nitrogen sorption isotherms. The concentration of the reagents and the reaction time affect the formation of this hollow‐flower‐ball‐like structure of this complex. The formation of this interesting structure may be attributed to the self‐assembly of smaller inorganic building blocks during the crystallization process of Cd4(OH)5Cl3 crystals. The photocatalytic activity of as‐prepared Cd4(OH)5Cl3 was evaluated by the degradation of salicylic acid and 4‐chlorophenol in water under UV‐irradiation.