ZnO-flaky-like nanoflowers with enhanced photocatalytic activity were synthesized by a new hydrothermal technique. The material was characterized and the photocatalytic studies were conducted under solar light irradiation for a model azo dye, Orange G. The material was compared with ZnO nanosphere and nanorod. The results showed the particle size of the nanostructures as a nanorod is 62–81 nm, as a nanosphere is 40–70 nm and as flaky nanoflowers is 20–30 nm (thickness of the flake). The photocatalytic activity showed an enhanced 2-fold increase in the activity for nanoflowers when compared to nanorods and spheres. The Brauner–Emmett–Teller results showed that the nanoflowers (14.197 m2 g−1) had a higher surface area nearly 3.5 times when compared to the nanospheres (4.06 m2 g−1) and seven times with nanorods (2.1 m2 g−1) which is the possibility of such high photocatalytic activity. The smaller particle size and the arrangement of nanoflowers play an important role in enhanced photocatalytic activity. Graphic abstract: ZnO flaky-nanoflowers as enhanced photocatalyst for the degradation of organics under solar light irradiation. It showed a two-fold increase in activity than ZnO nanospheres and nanorods.