3D nest-like ZnO nanostructures are synthesized via hydrothermal method operated at ambient temperature (80 ℃). The as-synthesized ZnO nanostructures are assembled by numerous ultrathin nanosheets resulting into formation of many grooves which improved the photocatalytic property. The as-synthesized ZnO sample is characterized by XRD, FESEM, FT-IR, Raman spectra, BET surface area and photoluminescence spectra analysis. Moreover, the photocatalytic efficiency of as-synthesized ZnO nanostructures is evaluated for degradation of methylene blue (MB) dye degradation. A comparision with the commercial counterpart reveals that the as synthesized nest-like ZnO degrades MB dye more efficiently. The present synthetic method can provide an effective route for synthesis of other hierarchically structured metal oxides also.