Bi₂WO₆ with multilayered disc-like and 3D hierarchical nest-like architectures self-assembled from 2D nanosheets were successfully synthesized by a hydrothermal method in EDTA-mediated processes. It was found that the morphology modulation of the as-obtained products could be easily realized simply by changing the amount of EDTA introduced into the reaction system. The stepwise self-assembly formation mechanisms for two different hierarchical architectures were proposed on the basis of a series of time-dependent experiments. The photocatalytic activities of the different Bi₂WO₆ samples for the degradation of Rhodamine B (RhB) were also evaluated. Due to the unique morphology, porous structure and large surface area, Bi₂WO₆ nest-like architectures exhibited better activity performance than Bi₂WO₆ multilayered microdiscs. The present work not only presents an efficient way for the selectively controllable preparation of Bi₂WO₆ hierarchical structures viaself-assembly from 2D nanosheets, but also provides a step forward in the design of photocatalysts with controllable morphology and enhanced photocatalytic activities.