Fluorinated Eu-doped SnO2 nanostructures with tunable morphology (shuttle-like and ring-like) are prepared by a hydrothermal method, using NaF as the morphology controlling agent. X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy are used to characterize their phase, shape, lattice structure, composition, and element distribution. The data suggest that Eu3+ ions are uniformly embedded into SnO2 nanocrystallites either through substitution of Sn4+ ions or through formation of Eu-F bonds, allowing for high-level Eu3+ doping. Photoluminescence features such as transition intensity ratios and Stark splitting indicate diverse localization of Eu3+ ions in the SnO2 nanoparticles, either in the crystalline lattice or in the grain boundaries. Due to formation of Eu-F and Sn-F bonds, the fluorinated surface of SnO2 nanocrystallites efficiently inhibits the hydroxyl quenching effect, which accounts for their improved photoluminescence intensity.