In this feature work, unique Bi/bismuth tungstate nanocomposites were fabricated using an in situ one step hydrothermal reaction by using ethylene glycol as the solvent. It is interesting to discover that not only the morphologies but also the composition of the products could be tailored by only adjusting the reaction temperature. When the reaction temperature was below 220 °C, an obvious shape evolution from irregular nanoparticle aggregations to hollow spheres to small nanorods was observed with increasing temperature; while when the temperature was higher than 220 °C, not only a new morphology but also a new phase of metal Bi appeared. In the as-prepared Bi/bismuth tungstate nanocomposites, the very tiny metal Bi particles formed during the in situ reaction dispersed very well on the surface of the bismuth tungstate nanorods, which made them exhibit excellent photocatalytic efficiency for the degradation of Rhodamine 6G (R6G). These results motivated us to perform a series of experiments to understand their formation mechanism and explore their physico-chemical insights while providing guidance to prepare novel metal/Aurivillius oxide nanocomposites for photocatalytic performance.