Various nitrogen‐doped hierarchical (BiO)2CO3 nanosheets architectures were synthesized by a facile one‐step template‐free hydrothermal method through controlling the hydrothermal temperature (HT). The as‐synthesized samples were characterized by XRD, SEM, FT‐IR, XPS, and UV‐vis DRS. The photocatalytic activity of the samples was evaluated towards degradation of NO at ppb level in air under visible light (VIL). It was found that HT acted as a crucial factor in determining the morphology of the samples. The rosa chinensis‐like, red camellia‐like, and lamina‐like of nitrogen‐doped (BiO)2CO3 (N‐BOC) micro‐/nanostructures can be selectively fabricated under hydrothermal temperatures of 150, 180, and 210°C. The thickness of the nanosheets was in direct proportion to the increasing HT. Nitrogen‐doping can extend the light absorption spectra of (BiO)3CO3 to visible light region and enhance the VIL photocatalytic activity. Especially, the red camellia‐like N‐BOC‐180 exhibited the highest photocatalytic performance, superior to the well‐known VIL‐driven photocatalyst C‐doped TiO2 and N‐doped TiO2. The high photocatalytic performance of N‐BOC was attributed to the synergetic effects of enhanced visible light absorption, multiple light‐reflections between the nanosheets, and accelerated transfer of reactants and product. This research could provide new insights to the development of excellent photocatalyst with efficient performance for pollution control.