In this critical review, hierarchical Bi₂MoO₆ nanostructures as photocatalysts for photocatalytically degrading organic materials are summarised in detail. Hierarchical nanostructures have attracted much attention due to their multiple advantages such as a porous structure, large surface area, efficient light harvesting and charge separation, which have considerable influences on the photocatalytic performance. Herein, the recent progress of hierarchical Bi₂MoO₆ nanostructures including primary, secondary and multiple structures is highlighted. Particularly, the morphologies, photocatalytic performance and mechanism of hierarchical Bi₂MoO₆ nanostructures are outlined. Finally, further development prospects of Bi₂MoO₆ photocatalysts are suggested. Hence, this systematic overview of hierarchical Bi₂MoO₆ will offer guidelines for designing efficient photocatalysts for environmental applications.