Bismuth tungstate is an important conductor and photocatalyst that keeps attracting research interest due to its promising catalytic activity under visible light irradiation. The 2D Aurivillius-type structure of Bi2WO6 promotes its tendency towards the formation of nanosheets that can be converted into hierarchically structured Bi2WO6 microspheres. As their formation mechanism varies strongly with the preparative parameters and further investigations are required, we present studies on the most direct and convenient access to Bi2WO6 nano-architectures developed hitherto. Our one-step approach towards this key material is based on the immediate hydrothermal reaction of Bi(NO3)3·5H2O with K2WO4 that proceeds through a mechanism that differs from the previously observed routes. These insights are essential for the development of straightforward technical processes in order to produce nanomaterials without complicated parameter adjustments. The resulting Bi2WO6 nanostructures display high photocatalytic activity under visible light irradiation. For the first time, the influence of an inorganic additive, K2SO4, is investigated in the Bi(NO3)3·5H2O/K2WO4 hydrothermal system. This paved the way to the synthesis and stabilization of other bismuth oxide-based materials at lower temperatures. Furthermore, we developed a flexible and efficient solution-based coating process to cover the hierarchical Bi2WO6 arrangements with a thin layer of anatase TiO2 nanoparticles.