•For the first time, 3D-hierarchical nanostructures are self-assembled at the aqueous–organic interfaces.•The strategy was energy-saving and time-efficient as it was conducted at room temperature within 30 min.•A relationship between the products and the aqueous–organic interfaces was proposed.This is the first time that uniform self-assembled 3D-hierarchical nanostructures were prepared at an aqueous–organic interface. Besides, the strategy is time and energy efficient, as it could be conducted at room temperature within 30 min. In order to investigate the influence of the nature of the interface to the nanostructure, a relationship between the morphologies and crystallinities of the products and the interfacial tensions of different aqueous–organic interfaces was investigated, and it was found that the flower-like crystalline nanostructures preferred generating at the interface with lower tension, and the spherical amorphous products were likely to form at higher-tension interface area, and fractal networks tended to occur at the interface with its tension between the above two.